Thai army soldiers prevent motorcyclists from entering a road at a checkpoint in central Bangkok on Tuesday. (Caren Firouz/Reuters)

Thai protest leaders said Tuesday they are ready for talks mediated by the speaker of the Senate to end violence in Bangkok.

"We have agreed to take a new round of talks proposed by the Senate because if we allow things to go on like this, we don't know how many more lives will be lost," Nattawut Saikua told a news conference at the red shirt protesters' fortified camp in central Bangkok.

The government's response was not immediately known.

At least 37 people — mostly civilians — have been killed and 266 wounded since the government began a blockade last Thursday on a sprawling protesters' camp in the heart of Bangkok. Most of the unrest has flared outside the camp, with troops firing live ammunition at roaming protesters who have lit tires to hide their positions.

Prime Minister Abhisit Vejjajiva's administration gave the anti-government demonstrators, who have been entrenched in the upscale Rajprasong district for more than a month, a Monday afternoon deadline to leave or face two-year prison terms.

By Tuesday, there was still no exodus among the estimated 3,000 protesters remaining at the camp, and no sign of troops trying to break through their tire-and-bamboo barricades.

Protesters seek new elections

The Red Shirts, many of whom hail from the country's impoverished north and northeast, have been rallying in the city since March 12 in attempts to unseat Abhisit and force immediate elections.

They say the coalition government came to power through manipulation of the courts and the backing of the powerful military, and that it symbolizes a national elite indifferent to their plight.

Previous attempts to negotiate an end to the standoff — which has destabilized a country once regarded as one of Southeast Asia's most stable democracies — have failed. A government offer earlier this month to hold November elections foundered after protest leaders made more demands.

The Thai government said late Monday that it would accept a cease-fire offer from a Red Shirt protest leader if their fighters end raging street battles and return to their main camp.

Sides remain far apart

Saikuwa called the government's chief negotiator, Korbsak Sabhavasu, on his mobile phone Monday, Korbsak said. It was the first direct talks between the two sides since the fighting started Thursday, though Korbsak said it was unlikely to achieve much as the two sides still remained far apart.

Nattawut's response was not immediately known. Calls to his phone went unanswered.

The UN high commissioner for human rights called for restraint on both sides and more talks.

"To prevent further loss of life, I appeal to the protesters to step back from the brink, and the security forces to exercise maximum restraint," commissioner Navi Pillay said in a statement from Geneva. "Ultimately, this situation can only be resolved by negotiation."