'Heavy fighting' in Afghan south

Nato forces are battling Taleban fighters regularly in Helmand

At least 26 suspected Taleban militants have been killed in clashes across southern Afghanistan, officials say.

A coalition spokesman said 10 insurgents had been killed in an air assault in Helmand province.

Other skirmishes are said to have taken place across the south.

Meanwhile, the Afghan Independent Human Rights Commission says that there has been a worrying increase in the number of civilian casualties in the south.

The commission estimates that 600 civilians have lost their lives this year as a result of the worsening conflict in Afghanistan.

It said that the vast majority were victims of Taleban suicide attacks, roadside bombs or assassination squads.

'Extremists'

The coalition says that the latest fighting in the south of the country is part of Operation Mountain Thrust, which was launched in mid-May.

"Coalition forces, supported by Afghan and coalition ground forces, conducted a night-time air assault into Sangin and killed 10 enemy extremists in a brief battle," a coalition statement said.

The assault involved more than 300 British paratroopers backed by US and Canadian forces.

UK troops take Taleban town

The offensive is the biggest operation undertaken by British troops in Afghanistan since the fall of the Taleban in 2001.

The coalition says that other skirmishes have taken place in the southern province of Uruzgan, with 31 insurgents killed since Friday.

Violence in southern Afghanistan has risen sharply this year, the bloodiest since 2001.

Coalition losses have been mounting, despite regular strikes against suspected militants.

The Human Rights Commission says that a growing number of innocent Afghan men, women and children have been caught up in coalition air strikes.

The government has ordered an inquiry in allegations that many civilians were accidentally killed in coalition air strikes in two different town over the past week.

The BBC's Mark Dummett says that ongoing insecurity in the south of Afghanistan makes it hard for anyone to establish the truth.