Taiwan's Seismology Centre said the first temblor measuring 6.8 on the Richter scale hit Taichung city, some 150 km south of capital Taipei at 8.14 am local time, followed by another half-an-hour later measuring 6.2 on the Richter scale, in Nantou city southeast of Sun Moon lake.

The fresh quakes triggered mudslides and caused cracks in the Sun Moon lake reservoir, one of the largest in the country, forcing authorities to evacate residents to safer places. The Seismological Department has predicted some more tremors in the next few days.

Meanwhile, the death toll in Tuesday's quake rose to 1,800. Over 4,000 were injured and 216 others were missing in the quake that rendered over 1,00,000 homeless, Taiwan's Disaster Management Centre saidon Wednesday. Most casualties were in the worst-affected counties of Taichung and Nantou.

Most deaths are believed to have been caused by the collapse of high-rise buildings, and the damage so far is estimated at some 3.2 billion US dollars, reports said.

Rescue teams and experts from countries like the United States and Singapore are expected in Taiwan to help local authorities to cope with the unprecedented crisis.

With a population of 2.7 million, the capital city of Taipei was spared much of the damage, though the quake destroyed a 12-storey hotel in the eastern part of the city.

The Taiwan Stock Exchange was closed for the second day on Wednesday due to power outages, but commercial banks and the foreign exchange market were set to work on Wednesday.

Meanwhile, Chinese seismologists have expressed concern about the quake. Zhang Guomin, a research fellow with the China Seismological Bureau was quoted by Xinhua news agency as saying the quake characterised by strong and frequent aftershocks,posed a threat to the life and property those living in quake areas.

The special geographical location of Taiwan island results in frequent quakes at its peripheral regions, Zhang said, adding while 85 per cent of the quakes jolt the sea floor, the epicentre of Tuesday's quake was located 10 km below the surface of the islands central land areas.