Thai Prime Minister Yingluck Shinawatra has rejected the demands of anti-government protesters who are attempting to topple her government and replace it with a ‘People’s Council’, saying they are unconstitutional.

“Anything I can do to make people happy, I am willing to do… but as prime minister, what I can do must be under the constitution,” she said in a televised address, her first comments since violence broke out late Saturday after weeks of peaceful protest.

The United Nations closed its main office in Bangkok, dozens of schools were shut and civil servants skipped work as stone-throwing protesters battled through clouds of tear gas in renewed assaults on key government buildings in the Thai capital on Monday, AP reported.

The protests aimed at toppling the government have renewed fears of prolonged instability in one of southeast Asia’s biggest economies and come ahead of the peak holiday tourist season.

After a weekend of chaos in pockets of Bangkok, protesters regrouped outside the heavily-barricaded prime minister’s office compound Monday and repeatedly clashed with police who fired tear gas, water cannons and rubber bullets.

Emboldened by their leader’s vow to topple Yingluck by Wednesday, they threw rocks at police and tore away sections of barbed wire and concrete barriers.

At least three people were killed and 103 injured in skirmishes over the weekend.

In a nationally televised appeal, Yingluck’s deputy, Surapong Tovichakchaikul, called on protesters to stop hurting Thailand’s image and the economy.

Yingluck has not appeared in public since Saturday, and has not been to her office since last week. On Monday, she posted a picture of herself on Facebook in a meeting with senior officials at the national police headquarters.

Using a conciliatory tone, Surapong said “the government will exercise utmost patience and adhere to nonviolent principles”.

“The government would like to insist that it will lead Thailand back to peace soon,” he said.

The protesters, who are mostly middle-class Bangkok supporters of the opposition Democrat Party, want Yingluck to step down, claiming she is a proxy for her brother, former Prime Minister Thaksin Shinawatra.

He was deposed in a 2006 military coup but remains central to Thailand’s political crisis, and is a focal point for the protesters’ hatred.

The protesters, who call themselves the People’s Democratic Reform Committee, say their goal is to uproot the political machine of Thaksin, who is accused of widespread corruption and abuse of power.

Monday’s violence took place around key institutions – the Government House, the Parliament and Metropolitan Police Headquarters in the historic quarter of the capital. The area has some of Bangkok’s main tourist attractions such as the Grand Palace, Wat Pho temple, the Bangkok zoo, and the backpacker area of Khao San Road. Most of Bangkok, a city of 10 million, has been unaffected.

Many of the protesters wore raincoats and plastic bags over their heads to protect against the sting of tear gas.

In an e-mailed statement to staff, the UN security department said “there could be violence (Monday) on a large scale … staff should avoid government offices” and other protest locations. It closed its main office near Government House, which houses several UN agencies.

The French Embassy issued one of the strongest warnings of dozens of foreign governments, urging citizens to “stay inside” to avoid the conflict on Bangkok’s streets. The French School is located in a northeastern Bangkok neighbourhood where gunshots rang out over the weekend during clashes between Yingluck’s supporters and opponents.