Syrian troops pushed Wednesday into a strategic town along the highway leading to the Jordanian border as a massive Internet outage engulfed most of the country for a second day.

The regime's advance into Khirbet Ghazaleh, a town south of Damascus along a key artery to the border, came after weeks of fighting and government attempts to secure the highway.

The push was part of a wider offensive against rebels in which President Bashar Assad's troops have regained some areas around Damascus, in the central province of Homs near the Lebanese border and in the region of Aleppo to the north.

The violence came as Iran, one of Assad's strongest allies, declared that it is ready to help any attempt to end Syria's crisis. In an opinion published in Lebanon's daily Al-Akhbar, Iranian Foreign Minister Ali Akbar Salehi wrote that it is up to the Syrian people to choose their political system and president.

It was not immediately clear if the government had pulled the plug on the Internet, triggering a blackout similar to a two-day outage that Syria experienced late last fall. Cellphone and phone services also were out in much of the country on Wednesday.

Syrian authorities have in the past cut phone and Internet service in selected areas to disrupt rebel communications when regime forces were conducting major operations. Widespread outages, however, have been rare.

The rebels and the government blamed one another for the blackout last year, which coincided with a major military operation in areas around the capital and near Damascus International Airport.

Syrian newspapers said Wednesday there was a technical problem in one of the cables and workers had started to fix it.

Meanwhile, the Britain-based Syrian Observatory for Human Rights and another activist group, the Aleppo Media Center, said opposition fighters shot down a fighter jet that was bombing rebel positions in the battle for the Mannagh air base near the border with Turkey.

Rebels stormed the besieged air base on Sunday and the fighting is now taking place inside the sprawling facility, the activists said. Also Sunday, the rebels downed a military helicopter in the eastern Deir el-Zour region, killing eight government troops who were on board.

Assad's forces on Wednesday attacked a military post they had lost to the rebels earlier in the northern town of Khan al-Assal, the two activist groups said.

The Observatory reported heavy fighting in Qusair, a town near the Lebanese border under government siege. Rami Abdul-Rahman, who heads the Observatory, said mediation is underway between people close to the regime and some regional "elements" to make the rebels withdraw from the town although many are still rejecting to leave.

As the violence continued on the ground, the United States and Russia, a key ally of Assad's government, said they'll convene a new international conference later this month to build on a transition plan they set out last year in Geneva.

Speaking in Moscow after his discussions with Russian President Vladimir Putin and other officials, U.S. Secretary of State John Kerry said the plan should be a roadmap for peace and not just a "piece of paper."

The goal is still to bring the Assad regime and representatives from the opposition together for talks on setting up an interim government, Kerry said Tuesday. The Geneva plan, which never gained traction, allowed each side to veto candidates it found unacceptable.

The Geneva proposal also calls for an open-ended cease-fire and the formation of a transitional government to run the country until new elections can be held and a new constitution drafted.

The international envoy to Syria, Lakhdar Brahimi, welcomed the Russian-U.S. initiative, saying it marks "the first hopeful news" concerning Syria "in a very long time."

"The statements made in Moscow constitute a very significant first step forward. It is nevertheless only a first step," Brahimi said in a statement.

Brahimi has expressed frustrations with the inability to find a political solution to Syria's conflict, and has lamented the divisions on the U.N. Security Council that have prevented any international action from being taken.

German Chancellor Angela Merkel declared support on Wednesday for the proposed U.S.-Russia international conference, saying that "it is a hopeful signal that the United States and Russia are now jointly proposing such a conference."

"The solution now must be a political one," she added. "We are convinced that President Assad has lost his legitimacy but we also know that we have to organize a political process within which the whole (transition) can be implemented."

Salehi, Iran's foreign minister who met Assad on Tuesday, wrote that he sees no solution in Syria other than Syrians "choosing their own fate, system and president through a fair and transparent political and electoral process." He added that "only the Syrian people are the ones who decide the political system in Syria and the name of the ruler."

"Iran is ready to make successful any fair initiative that guarantees the interests of the Syrian people and restores stability to this country," he wrote.

Syrian officials have said that Assad will stay in his post until his seven-year term ends next year and he will run again. The Syrian opposition says it will not accept anything less than Assad's departure.

Turkey's Foreign Minister Ahmet Davutoglu accused Syrian forces of "ethnic cleansing" in the coastal city of Banias, where activists said troops and pro-government Alawite gunmen killed at least 62 Sunnni Muslims last week.

"It is ethnic cleansing. The aim is to frighten people and drive them away," said Davutoglu in an interview with Turkey's Hurriyet newspaper. Although Sunnis are majority among Syrians and mostly back the opposition, the Syrian coast is inhabited by Christians and members of Assad's Alawite sect, an offshoot of Shiite Islam.

Meanwhile, in southern Syria, rebels were holding four U.N. peacekeepers who were abducted Tuesday near the Israeli-occupied Golan Heights.

The abduction was the second such incident in the area in two months. It exposed the vulnerability of the U.N. peacekeeping mission during the Syrian civil war and sent a worrisome signal to Syria's neighbors _ including Israel _ about the ensuing lawlessness along their shared frontiers.

Syria's two-year crisis that has so far claimed the lives of more than 70,000 people, according to the United Nations.

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Associated Press writer Juergen Baetz in Berlin and Suzan Fraser in Ankara, Turkey contributed to this report.