Image copyright AFP Image caption Local forces have been supported by the US and UK military in combating the Taliban in Helmand

One US service member has been killed and two wounded reportedly during a special forces mission in Afghanistan's southern Helmand province.

The forces were taking part in a counter-terrorism operation when they came under fire, US officials said.

One of two medical helicopter sent to rescue casualties is damaged on the ground and has yet to be recovered. The fighting is said to be ongoing.

About 12,000 foreign soldiers are still deployed to help tackle the Taliban.

Some of the foreign troops were sent to counter the recent militant insurgency in Helmand.

'Not shot down'

US military spokesman Brig Gen Wilson Shoffner said one service member had died as a result of wounds, adding: "We are deeply saddened by this loss... our heartfelt sympathies go out to the families and friends of those involved."

The identity of the casualties has not yet been revealed and no official details given on their service branch.

A number of Afghan forces were also reported to have been wounded.

Pentagon press secretary Peter Cook said: "This is an ongoing situation, there is still a fight going on in the immediate surroundings."

Two HH-60 Pave Hawk "medevac" helicopters were earlier dispatched to the scene.

One was forced to turn back after coming under fire, Mr Cook said.

Image copyright AP Image caption The helicopters involved were HH-60 Pave Hawks like these

It returned to base but the second, which landed safely at the scene, damaged its rotor blades after it apparently struck a wall, he said.

A US defence official said it was still on the ground and the military was working to recover it, but gave no further details.

In 2011, 30 Americans were among 38 people killed in a Chinook helicopter crash in Wardak province.

Helmand has long been a stronghold of the Taliban.

Afghan forces, aided by the US military, have been engaged in a fierce conflict recently with Taliban fighters who seized large swathes of Sangin district.

The fighting also sparked the deployment of a number of UK forces to Helmand for the first time in more than a year.

In September, the Taliban briefly overran the northern city of Kunduz in one of their biggest victories in 14 years of war.