A provincial security official says that Taliban fighters killed six Afghan policemen in an ambush in western Afghanistan.

Raouf Ahmadi, spokesman for the provincial police chief in Herat province, said Wednesday that six other police were wounded in the assault late Tuesday. Ahmadi said that eight Taliban fighters were also killed in the battle.

The Interior Ministry said Tuesday that more than 1,500 police have been killed in Taliban attacks over the last six months.

Afghanistan's security forces have faced increasing pressure on the battlefield this year as U.S. and other NATO forces continue to withdraw, resulting in higher casualties. Most U.S. and other NATO troops will leave Afghanistan by the end of the year.