Human Rights Watch Sunday called for the prosecution of Afghan militias loyal to dreaded former warlord Abdul Rashid Dostum, accusing them of killings and looting during an anti-Taliban operation.
The Junbish militia last month killed at least 13 civilians and wounded 32 in the northern province of Faryab after accusing them of supporting the Taliban, the New York-based rights group said.
It was the latest allegation of human rights abuses facing the militia controlled by Dostum, Afghanistan's first vice president who has a catalogue of war crimes attached to his name.
"The killings in Faryab are the latest in a long record of atrocities by Dostum's militia forces," HRW said in a statement.
"The fact that these forces, and Vice-President Dostum himself, have never been held accountable, has undermined security in northern Afghanistan."
The fearsome Uzbek general has sought to defend his home territory by reactivating private militias to fight Taliban insurgents, who are making steady inroads into northern provinces.
"They were carrying guns like Kalashnikovs and shouting 'You're Taliban!'
and firing as people came out of their houses," said a Faryab villager quoted in the HRW statement, referring to a recent raid by Junbish militiamen.
It also cited residents as complaining that the militiamen forced them to hand over food and money.
The Afghan government is cultivating numerous militias with chequered pasts in the region as a short-term security fix to supplement ground troops suffering record casualties.
But the rise of these groups, a throwback to the devastating civil war in the 1990s that set the stage for a Taliban takeover, risks aggravating factionalism and pushing Afghanistan deeper into conflict.
Civilian casualties, at the hands of both insurgents and of pro-government forces, are a matter of growing concern in Afghanistan.
The UN said civilian casualties soared to a record high in the first half of 2016, with children in particular paying a heavy price for growing insecurity as the conflict escalates.
It reported a 47 percent increase in casualties inflicted by forces loyal to the Afghan government.