NATO said it could not confirm whether an airstrike had hit the base.
Defense Ministry spokesman Gen. Mohammad Zahir Azimi said an Afghan army commando unit, district police members and foreign forces were in the base in the Bala Marghab district at the time of the airstrike Friday afternoon. Roauf Ahmadi, a spokesman for the western regional police commander, said the airstrike also wounded 15 Afghan soldiers and one policeman.
"During an air attack by NATO forces in Badghis province, seven Afghan forces were killed," the Defense Ministry said in a statement.
The ministry said NATO and Afghan authorities were investigating the incident and would issue a report soon.
On Friday, NATO headquarters in Kabul said more than 25 NATO and Afghan security forces members were injured during a search for two U.S. paratroopers missing from a resupply mission since Wednesday.
Five of those injured were NATO troops, said Lt. Col. Todd Vician, a spokesman for the alliance forces. He said it was not yet clear how they had been hurt. He said fighting had broken out Friday during the search for the missing paratroopers, and that close air support had been used.
Vician said no NATO soldiers had been killed in the operation.
Officials indicated it was unlikely the two missing personnel from the 4th Brigade Combat Team, 82nd Airborne Division, had been taken captive. Local police said the two Americans were swept away by a river in the western province of Badghis when they tried to retrieve supplies that had been airlifted and had accidentally fallen into the water.
NATO said the search and rescue operation was continuing Saturday.
Separately, the deputy governor of the southern province of Zabul, Ali Khail, said NATO forces raided an Afghan Red Crescent office in the city of Qalat early Saturday, killing a security guard and arresting three local Red Crescent employees.
NATO headquarters issued a statement saying coalition forces killed a militant and arrested "a few" suspected militants, including someone who was helping insurgents transport weapons and bomb-making materials to the area.