Anti-government protesters run for cover after police fires a tear gas shell to disperse them during a protest rally outside government offices which are barricaded by police forces in Bangkok, Thailand, Tuesday, Dec. 3, 2013.

BANGKOK - Thai anti-government protesters have broken through a gate and forced their way into the prime minister's office compound as police stood by and watched.

Hundreds of protesters poured onto the lawn of Government House, waving Thai flags and blowing whistles.

Earlier Tuesday, police used cranes to lift the barriers at Bangkok city police headquarters and then let protesters walk past police lines up to the Government House.

The unexpected reversal of strategy by the government comes after three days of bitter clashes between police and protesters who want to topple Prime Minister Yingluck Shinawatra's government.

She was not inside her office, which has been locked since Friday evening.