Two employees of Afghanistan’s Human Rights Body were killed in a bomb attack in Kabul on Saturday, the agency said.
The Afghanistan Independent Human Rights Commission said the pair died when a homemade “sticky bomb” attached to their vehicle exploded in the morning.
Kabul police spokesman Ferdaws Faramurz confirmed the attack, which has not been claimed by any group.
The United Nations Assistance Mission in Afghanistan condemned the killings.
“There can be no justification for attacks against human rights defenders,” it said on Twitter, calling for an immediate probe.
It comes less than a week after two prosecutors and three other employees from the attorney general’s office were shot dead by gunmen on the outskirts of Kabul.
On May 30, a television journalist was killed when a minibus carrying employees of private television channel Khurshid TV was hit by a roadside bomb in the city. That attack was claimed by the extremist Islamic State group.
Violence had dropped across much of the country after the Taliban offered a brief ceasefire to mark the Eid al-Fitr festival last month, but officials say the insurgents have stepped up attacks in recent weeks.