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

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

The U.S. Geological Survey measured Sunday's quake at a magnitude 7.2 and at a depth of 10 km (six miles).

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 on 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.