Kabul: Afghan and US-led coalition troops killed 27 suspected insurgents in two separate clashes in southern Afghanistan, the coalition said on Friday.

The fighting took place in the region at the center of the Taliban-led insurgency, where President Barack Obama has ordered thousands of new US troops to join the fight to try to reverse militant gains over the last three years.

The combined force killed 15 suspected insurgents Friday in fighting and airstrikes in Helmand province's Lashkar Gah district, the coalition said in a statement.

Daud Ahmadi, spokesman for the provincial governor, said up to 36 insurgents were killed and 18 others wounded, based on information provided by a local informant.

It was impossible to independently verify either claim.

Another 12 insurgents died in fighting Thursday in neighboring Uruzgan province, the coalition said.

There were no Afghan or coalition casualties in either clash, the statement said.

Separately, insurgents attacked a police checkpoint in Helmand's Nava district, killing six officers and wounding seven others, Ahmadi said.

The lightly armed police force has been hit hard by militants. Hundreds of officers died in militant attacks last year. Propping up the force, considered weak and beset by corruption, is one of the elements of Obama's Afghan strategy.

Obama plans to add 21,000 US soldiers and Marines to the 38,000 Americans already fighting across Afghanistan.

His strategy calls for an increased focus on boosting the capabilities of Afghanistan's security forces and improving the effectiveness of the government in Kabul.