Fires were still burning in central Bangkok after an overnight curfew that followed a day of riots and arson in which health officials said at least seven people were killed.

The Erawan Emergency Medical Center also said 81 people were wounded in the fighting at the protesters' camp in a commercial district in the heart of the capital and in skirmishes that broke out around the city.

It was uncertain whether the rioting represented a final outpouring of protesters' anger or whether it would intensify in days ahead.

The authorities said late on Wednesday that 27 buildings were set on fire by protesters, including Central World, Southeast Asia's second-biggest department store complex, which was gutted and looked close to collapse.

A spokesman for Bangkok's governor said there were 31 fires by Thursday morning, around half at banks but also including a mall in the protest camp area, where a fire had been started around midnight, after the curfew started at 8 p.m. (1300 GMT).

The curfew in the capital, in the grip of protests by "red shirt" activists for weeks, was lifted at 6 a.m. (2300 GMT on Wednesday). Buses began running but it was unclear if the mass transit rail system would be reopened.