HANGZHOU, China (AP) — The Latest on the G-20 summit in China (all times local):

2:10 p.m.

President Barack Obama is reassuring Turkey's President Recep Tayyip Erdogan that the U.S. will work to ensure those responsible for a failed coup are brought to justice.

Obama is holding his first meeting with Erdogan since this summer's coup attempt. Obama says he condemns the attempted overthrow.

The U.S. president also says it's critical to "finish the job" of securing Turkey's border with Syria. That's where Islamic State fighters have flooded into Turkey and would-be recruits into Syria.

Obama also says Turkey mustn't carry alone the burden of addressing the Syrian refugee crisis.

The leaders met on the sidelines of the Group of 20 economic summit in Hangzhou, China.

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12:45 p.m.

European Council President Donald Tusk says there will be no negotiations with Britain on the terms of its departure from the European Union until London formally invokes the two-year leaving process.

Speaking ahead of the G-20 summit in Hangzhou, China, Tusk said such pre-negotiations are not in the interests of the remaining 27 EU members.

Tusk says: "We need to protect the interests of the members of the EU that want to stay together, not the one which wants to leave."

Speaking earlier Sunday, British Prime Minister Theresa May said: "There will be no second referendum, no attempt to turn the clock back or get out of this. (Britain) will be leaving the European Union."

The U.K. has to invoke Article 50, the EU treaty clause that sets up the departure of a nation from the current 28-member bloc.

The Brexit, as it's known, is one of the main topics of concern at the economic forum.

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12:15 p.m.

President Barack Obama says he doesn't think disputes over media access during his trip to China reflect trouble in the U.S.-China relationship.

Obama says tensions always arise when the White House negotiated how much access the U.S. press will get to the president and foreign leaders overseas.

The White House doesn't apologize for pushing to press access because "we don't leave our values and our ideals behind when we take those trips."

But Obama says he wouldn't "overcrank" the significance of a shouting match that broke out between White House and Chinese officials as he arrived in China Saturday.

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12 noon

British Prime Minister Theresa May says there will be "no second referendum" in the U.K. on exiting the European Union. She says the U.K. will be leaving the EU.

May is meeting with President Barack Obama in China. She says the U.K. plans to continue pursuing an aggressive trade relationship with the U.S. despite the decision to leave the EU.

May and Obama are downplaying concerns that Britain becomes a lower trading priority for the U.S. by leaving the European bloc. The U.S. has been negotiating a broad EU trade deal and said ahead of the Brexit vote that Britain would go to the back of a line for a two-country deal if it left the EU.

Obama says he never said Britain would be punished. But he says it wouldn't make sense for the U.S. to lose focus on its European trade talks. He says the first priority for Britain now that it's leaving is to figure out its new trading relationship with its European neighbors.

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11:55 a.m.

President Barack Obama says U.S. and Russian negotiators are working "around the clock" to try to strike a deal to reduce violence in Syria but says "we're not there yet."

Obama is addressing the Syria crisis during a meeting with British Prime Minister Theresa May on the sidelines of the Group of 20 summit in China.

Obama says the U.S. is skeptical given the fact that previous cessations of hostilities have failed to hold. He says the negotiations are difficult and the U.S. and Russia have "grave differences."

But Obama says it's "worth trying" given Russia's role in supporting Syrian President Bashar Assad.

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11:45 a.m.

President Barack Obama says the U.S. and the U.K. will continue strengthening their "special relationship" even as Britain pursues its exit from the European Union.

Obama is holding his first meeting with new British Prime Minister Theresa May since she took over. He says the U.S. doesn't have a stronger partner in the world. Obama says the two countries will keep cooperating closely on cyber security, terrorism and trade despite the "turbulence" of recent political events. He's referring to the British vote to exit the EU, or Brexit.

May says the U.K. and the U.S. will "pursue the opportunities that Brexit presents." She says they'll "make a success of it."

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11:40 a.m.

Japanese Prime Minister Shinzo Abe arrived in China for the G-20 summit amid ongoing tensions between the Asian neighbors over claims to islands in the East China Sea.

It's Abe's first to China since attending the Asia-Pacific Economic Cooperation forum summit in November 2014 — itself a breakthrough following a freezing of high-level contacts by China in 2012.

That was part of Beijing's furious reaction to Tokyo's move to nationalize a string of tiny uninhabited islands controlled by Japan but claimed by China.

Japan regularly complains about the presence of coast guard Chinese ships in waters surrounding the islands, called Senkaku by Japan and Diaoyu by China, and a recent sail-by by a Chinese navy ship further raised tensions.

Abe is also routinely excoriated in China over his party's conservative views on history and efforts to expand the military's range of activity, a reflection of lingering anger over Japan's invasion of China just before World War II that is constantly stoked by Chinese propaganda.

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10:55 a.m.

U.N. Secretary-General Ban Ki-moon has touted what he called "the outstanding leadership" of the American and Chinese presidents, Barack Obama and Xi Jinping, for committing their nations to the Paris agreement on climate change.

At a news conference on the sidelines of the G-20 summit in Hangzhou, Ban urged other leaders to accelerate their countries' ratification process "so we can turn the aspirational Paris into the transforming climate action the world so urgently needs."

China and the United States, the world's top two carbon emitters, delivered documents to Ban on Saturday certifying that their countries have taken the necessary steps to join the Paris accord.

A total of 26 parties accounting for 39 percent of global emissions are signed up to the agreement that sets nation-by-nation targets for cutting carbon emissions.

The agreement still needs 29 parties representing at least 16 percent more of global emissions to enter into force.

The U.N. leader also praised China's organization of this year's G-20 summit and its focus on sustainable development. He commended the G-20 for "moving from a short-term focus on managing global financing challenges to a long-term vision for sustainable development."

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10:50 a.m.

The leaders of Brazil, Russia, India, China and South Africa held an informal meeting to reaffirm their loose alliance known as the BRICS group of emerging market powerhouses.

In opening remarks, Chinese President Xi Jinping said the bloc should grow alongside the Group of 20, which holds its summit Sunday afternoon in the eastern Chinese city of Hangzhou.

The BRICS leaders will meet again next month when they hold their own summit in India.

Xi also congratulated Brazil on holding a "successful Olympics," despite the fact neither he or any of the other BRICS leaders attended to avoid offending Brazilian sensitivities amid a bitter struggle over the country's leadership.

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7:20 p.m.

The United Nations' top climate official is thanking the United States and China for ratifying the global climate agreement reached in Paris.

Patricia Espinosa said in a statement Saturday that the accord offers an "opportunity for a sustainable future for every nation and every person." She added: "The earlier that Paris is ratified and implemented in full, the more secure that future will become."

The agreement will take effect 30 days after the date when 55 countries representing at least 55 percent of global emissions have formally joined it. The U.N. Framework Convention on Climate Change says the U.S. and China joining up brings the total so far to just over 39 percent.

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7:10 p.m.

Secretary of State John Kerry says the U.S. and China "demonstrated their continued, shared commitment to climate leadership" by formally joining the landmark climate agreement reached last year in Paris.

Kerry said in a statement that when the U.S. and China "come together to take action on climate, it moves the needle in a way that no two other nations can accomplish."

He added, however, that "it is essential for the Paris Agreement to enter into force as quickly as possible."

The agreement reached last year will go into effect if ratified by at least 55 countries representing 55 percent of the world's man-made emissions. Together, China and the United States represent 38 percent of the world's total.

Earlier Saturday, President Barack Obama and Chinese President Xi Jinping presented documents formally entering their countries into the climate agreement. China and the United States are the world's top two producers of man-made carbon emissions.

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6:50 p.m.

Chinese President Xi Jinping says the Group of 20's meetings should be transformed into a mechanism that delivers long-term guidance on the global economy, rather than one that just responds to crises.

Xi said in a speech Saturday that the G-20 was at a "crucial juncture," one day before its summit opens in the eastern Chinese city of Hangzhou.

The G-20 held its first leaders' summit during the 2008 economic crisis and now convenes annually with representatives from a mix of industrialized and developing economies.

China's hosting of the two-day summit is seen as part of its drive to cement its place among global economic leaders. In his speech Saturday, Xi said China would cut steel and coal production to reduce excess capacity and "sustain long-term development."