At least 200 militants have been killed over the past week as Afghan forces crack down on the Taliban in Nawa district of Helmand province, the police said on Sunday.The government forces backed by helicopter gunships have been targeting Taliban positions over the past week, Xinhua news agency quoted a senior police official as saying.The security forces would spare no efforts to restore stability in the troubled district, he said.Meanwhile, Taliban spokesman Zabihullah Majahid said the militants, who are in control of Nawa district over the past year, have foiled security forces' design to recapture the isolated district.Majahid claimed that nine security personnel were killed and the government forces offensive to recapture the district has been repulsed.Nawa, Marja, Sangin and a few more districts of the poppy growing Helmand province have been the scene of fierce fighting over the past few years.