An Afghan airstrike killed 10 security forces in volatile Helmand province on Sunday, an official said, as the military attempts to push back Taliban insurgents.

At least nine Afghan police were wounded in the "erroneous" airstrike in Gereshk district and an investigation is under way, Helmand governor Hayatullah Hayat told AFP. 

"The airstrike happened as Afghan forces were pushing to break through the Taliban frontline in the strategic area that has been the scene of heavy fighting over the past several days," Hayat said.