A Libyan rebel minister says Abdel Fatah Younes, the commander of the rebel armed forces, was killed by an allied Islamist militia.
Ali Tarhouni of the rebel National Transitional Council provided no motive for the assassination, which he said was still being investigated.
The killer or killers were still at large.
Libya's government spokesman, Musa Ibrahim, said Younes was killed by Al-Qaeda and that his killing proved the weakness of the rebel leadership.
Younes was a former Libyan interior minister who defected to the rebel side in February.
He was killed on July 28 along with two aides after being recalled to Benghazi for questioning.
Meanwhile, NATO said its warplanes had launched air strikes
on three Libyan television transmitter dishes overnignt. A spokesman said the aim of the strike was to stop broadcasts which were being used to incite violence and threaten civilians.
compiled from agency reports