ANTI-GOVERNMENT protesters occupied Thailand's Finance Ministry on Monday, laying out mats for eating and sleeping, in an escalating bid to overthrow Prime Minister Yingluck Shinawatra.
They also broke into the Foreign Ministry.
In response, Ms Yingluck on Monday night invoked the Internal Security Act to cover Bangkok, the neighbouring province of Nonthaburi, and nearby districts.
The occupation of both ministries came a day after more than 100,000 people gathered at Bangkok's Democracy Monument in their bid to oust the ruling Puea Thai party, which they deemed to be controlled by former prime minister Thaksin Shinawatra.
The self-exiled tycoon, whose sister is now PM, was deposed in a 2006 coup.
Sunday's protest was the biggest since 2010.
On Monday morning, more than 30,000 people led by the opposition Democract Party marched to 13 government offices and TV stations which they accused of biased coverage. The flag-waving, whistle-blowing marchers stopped traffic in the city.
"I invite protesters to stay here overnight at the Finance Ministry," key protest leader Suthep Thaugsuban told a crowd in front of the ministry, according to Reuters. The Democrat and former deputy premier resigned as a Member of Parliament two weeks ago to lead the protests.
Protesters first massed on the streets early this month against a Bill, backed by the Puea Thai, that would grant Thaksin amnesty for corruption-related offences. They later turned their attention to ousting the government.
One foreign photojournalist was assaulted on Monday after he was apparently singled out as pro-government.
Ms Yingluck urged protesters not to hurt public confidence by seizing government offices.
Chulalongkorn University political scientist Thitinan Pongsudhirak told The Straits Times: "She is buying time now, not going to resign and not going to use force."
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