An undersea earthquake measuring 6.3 on the Richter scale rocked Taiwan's buildings early Tuesday, shaking people from bed, but there were no immediate reports of casualties or damage.

The quake hit at 2:05 am (1805 GMT Monday), causing buildings to sway in most parts of the island, the Taiwanese Seismology Centre said.

It put the quake's epicentre at 57 kilometres (34 miles) east of Hsiulin, a town in the east of the island, with a depth of 9.4 kilometres under the sea.

It issued no immediate tsunami alert.

The United States Geological Survey put the quake's epicentre 137 kilometres south-southeast of the capital Taipei.

Taiwan, which lies near the junction of two tectonic plates, is regularly shaken by earthquakes. A 7.6-magnitude quake killed around 2,400 people in September 1999.

The island was hit by a series of tremors just over two weeks ago with the strongest reaching a magnitude of 5.6.