The Thai government has threatened to impose a curfew in Bangkok following three days of fighting that has killed at least 24 people.

The situation has spiralled into chaotic urban warfare with both the anti-government protesters and the military calling for reinforcements.

Prime Minister Abhisit Vejjajiva said a curfew was a possible step to restore order in the capital city of 15 million people known for its nightlife, as the army struggles to end weeks of increasingly violent protests seeking to topple his government.

The protesters remain defiant though, demanding the resignation of the British-born, Oxford-educated Abhisit, who they accuse of colluding with Thailand's royalist elite and meddling with the judiciary to bring down previous elected governments.

Hundreds of the red-shirted protesters have gathered on the road in working-class Klong Toey district since Saturday, many suffering gunshot wounds as they confronted nearby troops, hurling petrol bombs, rocks and crude homemade rockets.