Soldiers under attack in southern Afghanistan called in military bombers in a four-hour battle that left an "estimated two dozen enemy fighters killed," the US-led coalition said yesterday.

Afghan and coalition soldiers were attacked with rocket and gunfire Monday in the same area of Kandahar where soldiers from the separate Nato-led force came under fire the day before, leaving eight wounded.

"Coalition close air support was requested and munitions were dropped on three enemy positions," the coalition said in a statement.

"There were an estimated two dozen enemy fighters killed during the four-hour battle and no reports of Afghan civilian injuries," it said.

Meanwhile more than 30 Taliban militants drowned when a boat sank in southern Afghanistan, the defence ministry said Tuesday.

The boat sank after coming under fire from soldiers as it crossed the Helmand River on Monday carrying Taliban fighters escaping military operations, the defence ministry said.