KABUL, Afghanistan — Taliban militants in northern Afghanistan stoned a young couple to death for adultery, which a rights group said was the first confirmed use of the punishment here since the hardline Islamist regime was ousted in 2001.

The Taliban-ordered killing comes at a time when international rights groups have raised worries that attempts to negotiate with the Taliban to bring peace to Afghanistan could mean a step backward for human rights in the country. When the Islamist extremists ruled Afghanistan, women were not allowed to leave their houses without a male guardian, and public killings for violations of their harsh interpretation of the Quran were common.

The couple was discovered by Taliban operatives on Sunday and stoned to death in front a crowd of about 150 men, a local official said. The official said he decried the punishment, ordered by two local Taliban commanders. A spokesman for the provincial government also condemned the act.

“It is against all human rights and international conventions,” said spokesman Mabubullah Sayedi. “There was no court. It was cruel.”