Protesters in Thailand's capital Bangkok invaded the country's Finance Ministry compound, overrunning several buildings and cutting electricity.

Opposition-led protests started last month in an escalating campaign to topple Prime Minister Yingluck Shinawatra's government.

Protesters say they want the prime minister to step down amid claims that her government is controlled by her brother, former PM 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 as protesters fanned out to 13 locations across Bangkok, jamming traffic and raising concerns of violence.

"Go up to every floor, into every room, but do not destroy anything," Mr 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," urged the former deputy prime minister and opposition MP.

Protesters sang, danced and blew whistles in the hallways as part of their "whistle-blowing" campaign.

One group cut power at the Budget Bureau to pressure the agency to stop funding government projects.

Police made no immediate move to clear them out.

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

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.

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

Mr Thaksin's supporters and opponents have battled for power since he was toppled in 2006 following street protests and fled the country.

The former PM has lived in self-imposed exile for the past five years to avoid a prison sentence for corruption.