A severe tropical storm has swept across southern Taiwan, damaging houses, overturning cars, and toppling many trees after thousands of people were evacuated from their homes ahead of the disaster.

Typhoon Tembin started heavy floods in towns across Taiwan's southern coasts and left thousands of homes without power on Friday, Taiwan's Central Weather Bureau said.

The typhoon dumped nearly 50cm of rain in Pingtung county overnight, leaving four towns flooded in knee-deep brown water. 

Television images showed rescuers and soldiers navigating through empty streets in rubber boats, while heavy-duty military trucks ploughed through the water to rescue trapped residents.

Fallen tree trunks covered roads in the affected areas, and in the coastal village of Tawu, a number of rooftops were blown off by strong winds.

A line of electricity poles in the county were also toppled by the storm, cutting off power to tens of thousands of homes.

Across the island, more than 50,000 households were without power, according to the state Taiwan Power Company.

There were no reports of casualties, but farmers said their livelihoods had been badly affected by the powerful weather system.

In towns along the east coast, some 6,500 people were evacuated and schools and businesses shut down as communities braced for the typhoon to hit, but Tembin made landfall further south than expected.

The weather bureau said the typhoon appeared to have lost strength as it passed over Taiwan's mountainous southern terrain, and was now moving out to sea on a looping path.

Fears over typhoon return

As of 0515 GMT, the typhoon was about 30km southwest of Taiwan's southern city of Kaohsiung, according to the Central Weather Bureau, which said it could circle back.

"Today and tomorrow will be a crucial time. It may come back. It's determined by a multitude of factors," said weather bureau forecaster Lo Ya-yin. 

The high-speed rail service linking Taipei to Kaohsiung city in the south cut its services to three trains per hour, down from up to six per hour. The company said they expected to resume normal operation from 0800 GMT. 

The evacuations were ordered in risk areas along Taiwan's coastline as authorities attempt to prevent a repeat of an enormously destructive typhoon which hit three years ago.

Typhoon Morakot killed about 600 people in August 2009, most of them buried in huge landslides in the south.

A senior military official told AFP news agency on Thursday that authorities had learned lessons from Morakot, when they "had not done enough evacuations beforehand".

Taiwan's military had ordered 50,000 soldiers to be on standby, ready to move out and assist in disaster prevention efforts. 

Source: Agencies