Nearly 40 suspected militants have been killed in fierce clashes with US and Afghan forces in southern Afghanistan, the US military has said.

The clash occurred after fighters attacked a security patrol near Daychopan district in Zabul province, a military statement said.

An Afghan policeman was killed and five American soldiers were wounded.

There has been renewed violence in Afghanistan in recent months blamed on the Taleban and their allies.

US military spokesman said the fighters were killed during an intense 11-hour-long battle in the mountainous Daychopan area.

Wave of violence

The fighting began after Afghan and coalition forces were attacked by fighters with small arms and rocket propelled grenades on Tuesday, according to a US military statement.

The forces were patrolling an area south-west of Daychopan when the attack took place.

"Coalition warplanes and attack helicopters were hammering enemy positions throughout the evening," the statement said.

Two of the helicopters were damaged during the fighting.

Some 23 fighters had been captured after the clashes, Afghan police commander Gen Salim Khan told the Associated Press.

"There are hundreds of Taleban in camps in the mountains. My officers have been spotting them and then the information is used by American aircraft to bomb them," he said.

Gen Khan said many rebels had begun to "flee the area".

Accusation

US military spokesman Lt Col Jerry O' Hara said that the operation to flush out rebels from the area was continuing on Wednesday.

This mission is an ongoing effort to take away enemy sanctuaries, he said.

"We are not letting up on the enemy and will continue to pursue them until the fighting stops."

Tuesday's incident follows a wave of violence earlier this week in which at least 38 fighters were killed in clashes with US-led coalition and Afghan forces in southern Afghanistan.

The BBC's Andrew North in Kabul says that barely a day goes by now without serious violence across south and east Afghanistan.

This has led the Afghan government to accuse neighboring Pakistan of not doing enough to rein in militants who it believes are sheltering there.

Washington is concerned too at the rise in tension between two countries who are both key allies in its war on terror. On Tuesday President Bush called Pakistani President Pervez Musharraf, who in turn called his Afghan counterpart, Hamid Karzai.

The US has about 18,000 troops in Afghanistan tackling remnants of the Taleban that was ousted in late 2001.

Violence has increased, particularly in the south and east, following a lull over winter, raising fears for security in September's planned parliamentary elections.

Nearly 400 people have been killed in Taleban-linked violence this year, most of them suspected militants but also around 30 US troops.

PHOTO CAPTION

Taleban fighters