A tour bus carrying tourists from China has burst into flames on a busy road near Taiwan's capital, killing all 26 people on board, officials said.

The accident happened on the No 2 national highway in Taoyuan county, where the island's international airport is located, the county fire and rescue service said in a statement.

It said 24 of those on board were visitors from China's Liaoning province who had been due to fly home on Tuesday afternoon. The others killed were the driver and a tour guide, both Taiwanese.

The website of Taiwan's China Times newspaper said no-one on board had managed to escape from the burning bus, and that many of the bodies had been badly charred.

The cause of the fire was not immediately known, although Taiwan's official Central News Agency and others reported that the bus apparently burst into flames after spinning out of control and crashing into the highway's guard rail. However, the exact sequence of events was unclear.

Photos from the scene showed flames and thick black smoke pouring from the cab of the bus shortly after the crash.

Thirteen firefighting vehicles and 30 firefighters were sent to the scene, but the blaze apparently spread too rapidly and, once the flames were extinguished, the vehicle was heavily blackened from one end to the other.

AP