A STRONG earthquake rattled Taiwan island this morning, but no injury has been reported, local media said.

The 6.6-magnitude earthquake struck at sea, 74 kilometers southeast of the eastern city of Ilan at 1:51am, Taiwan's weather bureau said.

The temblor was felt 10 to 13 seconds in Ilan and 20 seconds in Taipei, 80 kilometers of Ilan, the bureau said.

Seven aftershocks hit the island by 4:20am and the bureau forecasted that 5-magnitude aftershock is still likely to happen in east Taiwan in the following week.

It is the third strongest earthquake that shakes Taiwan since the deadly 7.6 magnitude earthquake on September 21, 1999 that killed 2,415 people and injured more than 10,000 others.