Afghan security officials said an operation aimed at freeing a group of kidnapped civilians in southern Afghanistan was continuing after a battle on March 4 killed dozens of militants but failed to secure the hostages' release.
Masked gunmen seized about 30 passengers from two buses in the southern province of Zabul last month as they were traveling late at night toward Kabul on Afghanistan's main ring-road highway.
Most of the kidnapped passengers were members of the ethnic Hazara minority, a group that was persecuted by the mainly Pashtun Taliban regime.
Local officials in Zabul Province say about 50 militants were killed when Afghan security forces launched an operation to free the hostages.
Afghan National Army General Abdul Hameed said 21 of those killed were "foreign fighters" without specifying their nationality.
But Afghanistan's Deputy Vice President Sarwar Danish said more than 100 militants were killed in an operation launched after negotiations on freeing the group broke down.
Afghanistan's Taliban has not claimed responsibility for the mass kidnapping.