KABUL (AFP) - Seven members of the Afghan security forces were killed in a Nato airstrike in remote western Afghanistan, the Afghan Defence Ministry said on Saturday. Due to a Nato forces airstrike on November 6 in Badghis province seven Afghan security personnel (both Afghan army and national police) were martyred and also some were wounded, the Ministry said in a statement. The commando brigade informs us that foreign forces also sustained some casualties, it said, adding: The issue is under investigation by Afghan and NATO forces and the results will be announced soon. The statement came as Natos International Security Assistance Force (Isaf) said it was investigating an incident Friday in which more than 25 international and Afghan forces were killed or wounded. Five of the wounded were US soldiers, injured in what a Western military official, speaking anonymously, said was friendly fire. However, Isaf spokesman Lt-Col Todd Vician, of the US Air Force, told AFP: We have nothing to confirm friendly fire. No Isaf members were killed, he said, confirming that five injured Isaf soldiers were Americans. A later Isaf statement said, Isaf and Afghan authorities are currently investigating whether some of the casualties were caused by Isaf close air support. It said the incident occurred during a clash involving Isaf and Afghan soldiers searching for two soldiers who went missing Wednesday while attempting to recover airdropped supplies from a river in western Afghanistan. The casualties came during a joint operation that involved multiple engagements over several hours yesterday (Friday) in the west of the country, it said. Meanwhile, at least three Afghan soldiers and more than a dozen Taliban were killed on Saturday when an army convoy was struck by a roadside bomb in Girishk district of troubled Helmand province, southern military corps commander Gen Shair Mohammad Zazai told AFP. Separately, a joint raid by the Afghan army and international forces on a compound in Naw Bahar district, in neighbouring Zabul province, killed 18 Taliban fighters, he said. The bodies of all 18 militants were recovered from the compound, along with weapons and vehicles, he said. In Qalat, capital of southern Zabul province, Afghan and international forces killed one militant and captured three others, including a suspected Taliban IED facilitator who had taken refuge in an Afghan Red Crescent office, Nato said in a statement. After a firefight in which the militant was killed, the joint force searched the compound and detained the militants, including the facilitator, Natos International Security Assistance Force (ISAF) said. Another operation, conducted overnight Friday by Afghan soldiers in Zabuls Mizan district, resulted in the deaths of four militants, Zazai said.