Anti-government demonstrators in Thailand have broken into the Foreign Ministry compound after taking over the Finance Ministry in their offensive against the administration of Prime Minister Yingluck Shinawatra.

Foreign Ministry spokesman Sek Wannamethee says a group of protesters forced their way into the ministry premises Monday evening but promised not to enter its buildings. He was uncertain how many there were.

Protesters say they want Yingluck to yield power amid claims that her government is controlled by her brother, former Prime Minister Thaksin Shinawatra, who was ousted in a military coup in 2006. On Sunday, more than 150,000 demonstrators took to Bangkok's streets in the largest rally Thailand has seen in years, uniting against what they call the "Thaksin regime."

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

Protesters in Thailand's capital swarmed the Finance Ministry compound Monday, overrunning several buildings and cutting electricity in an escalating campaign to topple Prime Minister Yingluck Shinawatra's government.

The intrusion was the boldest act yet in opposition-led protests that started last month. It highlights the movement's new strategy of paralyzing the government by forcing civil servants to stop working.

Protesters say they want Yingluck to step down amid claims that her government is controlled by her brother, former Prime Minister Thaksin Shinawatra, who was ousted in a military coup in 2006. On Sunday, more than 150,000 demonstrators marched in Bangkok in the largest rally Thailand has seen in years.

Protest leader Suthep Thaugsuban led the crowd at the Finance Ministry on a day when protesters fanned out to 13 locations across Bangkok, snarling traffic and raising concerns of violence in the country's ongoing political crisis, which has revolved around Thaksin for years.

"Go up to every floor, go into every room, but do not destroy anything," Suthep told the crowd before he entered the ministry and held a meeting in its conference room.

"Make them see this is people's power!" said Suthep, a former deputy prime minister and opposition lawmaker.

Protesters sang, danced and blew noisy whistles in the hallways as part of their "whistle-blowing" campaign against the government. One group cut power at the Budget Bureau to pressure the agency to stop funding government projects.

Police made no immediate move to oust them.

More than two dozen Bangkok schools along the protest route were closed Monday and police tightened security at the protest destinations, which included the military and police headquarters and the five television stations controlled by the military or the government.

Despite a heavy police presence at most protest sites, there was limited security at the Finance Ministry.

At another protest near the prime minister's office, police were outnumbered by more than 1,000 protesters who scuffled with officers and tore down a razor wire barricade. A foreign freelance journalist in the crowd was punched by protesters who accused him of biased reporting before security personnel intervened.

Many fear that clashes could erupt between the anti-government protesters and Thaksin's supporters, who are staging their own rally at a Bangkok stadium and have vowed to stay until the opposition calls off its demonstrations.

Thaksin's supporters and opponents have battled for power since he was toppled in 2006 following street protests accusing him of corruption and disrespect for the country's constitutional monarch, King Bhumibol Adulyadej. Thaksin has lived in self-imposed exile for the past five years to avoid a prison sentence on a corruption conviction.

The battle for power has sometimes led to bloodshed on Bangkok's streets. About 90 people were killed in 2010 when Thaksin's "Red Shirt" supporters occupied parts of central Bangkok for weeks before the government, led then by the current opposition, sent the military to crack down.

The latest protests have ended two years of relative calm under Yingluck's government.

Yingluck's administration has struggled to contain the demonstrations, which started over opposition to a government-backed political amnesty bill that critics said was designed to bring Thaksin home from exile. The Senate rejected the bill earlier this month in a bid to end the protests. But the rallies have gained momentum and leaders have now shifted their target to the goal of toppling the "Thaksin regime," which is how protesters refer to Yingluck's government.

The intrusion at the Finance Ministry raised the specter of a repeat of 2008 protests when Thaksin's opponents were protesting a different Thaksin-allied government and occupied the prime minister's office compound for three months.