Anti-government protesters take cover after throwing a gasoline bomb in Bangkok on Sunday. (Vincent Yu/Associated Press)

Rapid gunfire and explosions echoed before dawn Monday outside the luxury hotels bordering the barricaded protest zone in Bangkok after Thai authorities rejected an offer from protest leaders to take part in UN-mediated peace talks to end the chaos.

A Reuters photographer reported heavy fighting during the night at the upscale Dusit Thani Hotel opposite one of the barricades set up by the protesters around their encampment.

The government said Sunday its moves against the Red Shirt anti-government demonstrators will continue and it called on their leaders to surrender.

At least 30 people have been killed in four days of street fighting.

A pause by the Thai military is unnecessary since troops are "not using weapons to crack down on civilians," said government spokesman Panitan Wattanayagorn. The government maintains it is only targeting armed "terrorists" among the demonstrators.

In a sign the military may escalate efforts to dismantle the camp, the army called on protesters to remove all women, children and the elderly from behind the barricades by Monday afternoon.

Red Cross workers could be seen Sunday helping with the evacuation. Hundreds of people have been bused to a Buddhist temple compound near the protest zone.

Troops and army sharpshooters have surrounded the three-square-kilometre area in downtown Bangkok, where anti-government demonstrators have erected barricades of tires, sandbags and bamboo spikes.

Supplies not reaching protest zone

The protest camp, set up in mid-March, is said to be running out of food, water and other supplies. Between 3,000 and 5,000 protesters remain behind barricades in the Ratchaprasong commercial district, according to local media.

About 10,000 protesters were camped out before fighting started Thursday after a sniper shot and seriously wounded a Red Shirt leader, a former army general whose condition worsened Sunday.

The latest deaths raise to 59 the number of people killed since April 10.

Thailand's main emergency medical centre said 232 people have been wounded in clashes that began Thursday. Erawan Emergency Center said Sunday all those killed in recent days were civilians.

Security forces have used tear gas, rubber bullets and live rounds on demonstrators, who are armed with gasoline bombs, slingshots and sharpened bamboo sticks.

The military cancelled plans to impose a nighttime curfew Sunday, but the centre of the Thai capital still resembles a curfew zone with no public transport or private vehicles in view.

Most shops, hotels, supermarkets and businesses in the area are closed, while the government has shut off power and water to the core protest zone.