A 6.8 magnitude earthquake hit the sparsely populated southeastern part of Taiwan today, the island's weather bureau said, derailing train carriages, causing a convenience store to collapse, and trapping hundreds on mountain roads.

The US Pacific Tsunami Warning Center issued a warning for Taiwan after the tremor but later lifted the alert. Japan's weather agency lifted a tsunami warning for part of Okinawa prefecture.

The weather bureau said the epicentre was in Taitung county, and followed a 6.4 magnitude temblor yesterday evening in the same area, which caused no casualties.

The US Geological Survey measured today's quake at a magnitude 7.2 and at a depth of 10km.

Taiwan's fire department said all four people were rescued from a building housing a convenience store that collapsed in Yuli, while three people whose vehicle fell off a damaged bridge were rescued and taken to hospital.

The Taiwan Railways Administration said six carriages came off the rails at Dongli station in eastern Taiwan after part of the platform canopy collapsed, but the fire department said there were no injuries.

More than 600 people are trapped in the scenic Chike and Liushishi mountain areas by blocked roads, though there were no injuries and rescuers were working to reopen the roads, the department said.

The quake could be felt across Taiwan, the weather bureau said. Buildings shook briefly in the capital Taipei, and aftershocks have continued to jolt the island.

Science parks in the southern cities of Tainan and Kaohsiung, home to major semiconductor factories, said there was no impact on operations.

Taiwan Semiconductor Manufacturing Co (TSMC), the world's largest contract chipmaker, said there was "no known significant impact for now".

Taiwan lies near the junction of two tectonic plates and is prone to earthquakes.

More than 100 people were killed in a quake in southern Taiwan in 2016, while a 7.3 magnitude quake killed more than 2,000 people in 1999.

- Reuters