BANGKOK — Thailand's government insisted Sunday a crackdown on Red Shirt protesters will continue despite their plea for U.N-mediated talks to end four days of street clashes with troops that have left 30 people dead.

A pause by the Thai military was unnecessary since troops were "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.

Panitan's comments dashed hopes of an end to Thailand's worst political violence in decades, which has spiraled out of control and raised concerns of sustained, widespread chaos in this nation of 65 million people. Thailand is a key U.S. ally and Southeast Asia's second-largest economy.

According to government figures, 59 people have died and more than 1,600 have been wounded since the Red Shirts began their protests in March. The toll includes 30 civilians killed and 232 injured since Thursday in fighting that has turned parts of the city known for its nightlife into an urban war zone.

A towering column of black smoke rose over the city Sunday as protesters facing off with troops set fire to tires serving as a barricade. Elsewhere, they doused a police traffic post with gasoline and torched it as sporadic gunfire rang out.

The Red Shirts have occupied a 1-square-mile protest zone -- barricaded by tires and bamboo spikes -- in one of Bangkok's ritziest areas since mid-March to push their demands for Prime Minister Abhisit Vejjajiva to resign immediately, dissolve Parliament and call new elections.

Drawn mostly from the rural and urban poor, the Red Shirts say Abhisit's 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 the poor.

Soldiers have encircled the protest zone in a wide perimeter. Most of the fighting is taking place in the no-man's land in between. The Red Shirt fighters have used homemade gasoline bombs, firecrackers, rocks -- and in some cases guns -- to attack troops positioned behind sandbag bunkers. The soldiers have responded with rubber bullets and live ammunition.

Journalists have seen army snipers take aim through telescopic sights and fire to keep the attackers at bay.

With the Red Shirts' encampment virtually sealed off by troops, the protesters are running out of food and water and other supplies.

"We are willing to negotiate immediately," Nattawut Saikua, one of the protest leaders, told reporters and supporters earlier Sunday. "What's urgent is to stop the deaths of people. Political demands can wait."

Nattawut said the United Nations must serve as a mediator in the talks because, "we don't see any neutral and just organizations."

In response, Panitan said all groups using weapons to threaten security forces must "stop their actions immediately."

Thailand is a sovereign nation and there was no need for the U.N. to get involved in internal matters, he said.

A state of emergency, already in effect in 17 provinces, would be extended to five more provinces, Panitan said. The emergency bans a gathering of more than five people and gives the military broad powers.

On Sunday, protest leaders told women and children with them to move to a Buddhist temple compound within the protest zone. In Thai tradition, temples are considered safe havens and will not be entered by anyone bearing arms.

But many of the worst clashes Sunday were outside the protest zone with particularly fierce battles in a working class neighborhood where a large group of demonstrators gathered -- an indication the unrest was spreading.

About 5,000 people are believed camped in the main protest zone, down from about 10,000 before fighting started Thursday after a sniper shot and seriously wounded a Red Shirt leader, a former army general who was their military strategist. His condition worsened Sunday, doctors said.

The urban battleground resembles a curfew zone with no public transport or private vehicles. Most shops, hotels, supermarkets and businesses in the area are shut. The government has shut off power, water and food supplies to the core protest site.

Schools were ordered shut Monday in all of Bangkok. Long lines formed at supermarkets outside the protest zone as people rushed to stock up on food.

The clashes are the most prolonged and deadliest bout of political violence that Thailand has faced in decades despite having a history of coups -- 18 since it became a constitutional monarchy in 1932.

The crisis appeared to be near a resolution last week when Abhisit offered to hold elections in November, a year early. But the hopes were dashed after Red Shirt leaders made more demands.