Two strong tremors rattled Taiwan's capital early on Friday, officials and witnesses said, but there were no immediate reports of serious damage or casualties.

The U.S. Geological Survey measured the magnitude of the first quake at 6.5 at 01:51 am local time. Taiwan's Central Weather Bureau said a second tremor followed four minutes later with a magnitude of 5.7.

A Reuters journalist in Taipei said the quakes, which each lasted around 10-15 seconds, shook his building and knocked pictures off the walls.

Spokesmen for Taiwan Semiconductor Manufacturing Co Ltd, the world's top contract chip manufacturer, and CPC, Taiwan's top oil company, said they had not been informed of any disruptions or casualties.

The Central Weather Bureau put the epicenter of the first quake was 76 km (47 miles) southeast of the island nation and 27 km deep and the second one about 10 km farther away.

Taiwan's disaster centre said they had no reports of casualties.

Earthquakes are common in Taiwan but do not often cause serious damage. The worst in recent years was in 1999, when at least 2,000 people died in a quake measuring 7.6 in central Taiwan.