NATO's British forces were on Tuesday checking a report that some civilians were killed during an operation against the Taliban insurgents in Afghanistan's southern province of Helmand, a spokesman said.

Hundreds of Afghans were been killed in air strikes and raids by foreign troops last year, undermining public support for the presence of international forces and leading to a rift between President Hamid Karzai and his Western backers.

The latest incident happened in Baghni district on Monday night when, according to a provincial government source, five members of a family were killed in an operation by British forces.

No further details were given by the official.

"We are looking into this," Major Steve Melbourne, a spokesman for the British forces in Helmand, said by phone.

Nearly 700 civilians were killed up to October last year in raids by foreign and Afghan forces, an Afghan rights body said last month, quoting a U.N. estimate.