Troops backed up by armoured vehicles have tightened their grip on the city

Civilians and protesters loyal to former premier Thaksin Shinawatra clashed overnight in Bangkok, as tensions rose across the capital after a military crackdown on the protest movement. The protestors have been calling for fresh elections and want former prime minister Thaksin Shinawatra, who was ousted in a coup in 2006, to be reinstated.

The red-shirted protesters, who had managed to shut down parts of Bangkok for the past three weeks, are demanding the resignation of Prime Minster Abhisit Vejjajiva.

Overnight the army hemmed in the several thousand activists, following a day of violent clashes with police and soldiers that left more than 120 people injured. More soldiers then moved in, prompting the protest leaders to call on their remaining followers to go home to avoid further bloodshed. The activists were searched for weapons as they left, and the security service brought in 60 buses to transport them from the prime minister's office. Most of the leaders have now turned themselves over to authorities, others have gone into hiding.

This morning the protest leaders decided it was time to surrender and most of the protesters have headed home. The police say the leaders will face prosecution, and one has already been arrested. Police have also detained three men who reportedly threatened to set fire to commercial buildings in the busy Silom district. Thailand's national police chief says protest organisers will be prosecuted for violating a state of emergency banning large gatherings.

Burnt buses still blocked Bangkok streets on Tuesday

Some of the protesters say they will continue the campaign against Mr Abhisit's government, which replaced an elected government allied to Mr Thaksin in December. There are reports today that Thai authorities have asked Interpol to help track Mr Thaksin down.

There have been several flare-ups in different areas, including the burning of a bus in one part of the city. The military says it now has control of several intersections which were overrun by the protesters on Sunday night. Businesses and stores are expected to remain closed today.

Meanwhile, the Thai Government says it is no longer prepared to negotiate with Mr Thaksin. Mr Thaksin has been seeking a royal pardon for his corruption conviction and last night some of his political allies filed a petition requesting intervention by King Bhumipol Adulyadej.