Mullah Dadullah has been called "Afghanistan's top Taliban commander" by NATO officials. The body of a man thought to be Dadullah has been shown to journalists.
A NATO statement today says Dadullah, a commander who trained suicide bombers, was killed after he left what was described as his "sanctuary" in southern Afghanistan.
A spokesman for Afghanistan's National Security Service, Saied Ansari, told RFE/RL's Radio Free Afghanistan earlier today that Mullah Dadullah had been killed during a battle in the southern Afghan province of Helmand.
The Afghan Defense Ministry says Dadullah's body was discovered among about a dozen dead Taliban fighters left behind on the battlefield by fleeing militants.
Meanwhile, authorities in Kabul say Afghan and foreign coalition troops killed 55 suspected Taliban fighters on May 12 during two separate military operations near Afghanistan's border with Pakistan.
That fighting, which also killed one Afghan police officer, was in the southeastern province of Paktia.
A spokesman for the NATO-led International Security Assistance Force in Afghanistan said he did not have any details about those operations.
Separately, an Afghan police officer was killed by a roadside bomb today in the eastern province of Nangarhar.
(with materials from agency reports)