A U.S. service member was killed and two were wounded in Afghanistan's Helmand province, U.S. officials have reportedly said.

According to reports, the U.S. forces in Afghanistan were involved in two separate incidents, one with helicopter and another in counter-terrorism operation.

"We are deeply saddened by this loss," said Brigadier General Wilson A. Shoffner, the spokesman for the NATO mission in Afghanistan, adding "our heartfelt sympathies go out to the families and friends of those involved".

A US defence official told AFP on condition of anonymity that it was a special operations mission and Afghan soldiers were also wounded.

NBC, citing officials, has said that the forces came under heavy mortar and small arms fire in Southern Afghanistan.