A military helicopter has crashed in the south of Afghanistan, killing 17 people, the chief of police in Zabul province has said.
Mirwais Noorzai said the Afghan National Army helicopter crashed in a remote region of the province on Thursday morning, leaving five pilots and 12 soldiers dead.
Moorzai said the cause of the crash was unknown and is under investigation.
The Defence Ministry said the crash was believed to be caused by a technical problem, but provided no further details.
Afzal Aman, the Defence Ministry's chief of operations, described it as "the worst calamity to hit the air force."
He confirmed the casualty figure, and said the dead included a unit commander and 11 soldiers, as well as the crew.
Aman said the helicopter was a Russian-made M-17, and was flying between Zabul's capital Qalat and Shinkay, 20km away.
The Taliban issued a statement on their website taking responsibility.
The crash is among the worst suffered by the Afghan military since US and NATO forces concluded their combat mission at the end of last year, transitioning to a support and training role.