Questions have been raised over the death Libyan rebel leader General Abdul Fatah Younes after reports he was shot by an armed gang were disputed.

Instead, some claim he was killed by fellow rebels, leading to tension within the national Transitional Council – the body that Britain officially recognised as representing Libya on Wednesday.

The military chief had been interior minister under Libyan leader Muammar Gaddafi before defecting to the rebels, but he was recently said to have been called in for questioning by opposition judges over suspicions he had remained in contact with the regime.

Mustafa Abdul-Jalil, the rebel leader and head of the Transitional National Council (TNC) in Benghazi, said Younes and two aides were killed by gunmen after he was recalled for questioning.

But the Guardian reported there was uncertainty over two bodies found after Younes' death, writing:

Jalil said that rebels had arrested the head of the group behind the attack but the bodies of Younes, Muammar Gaddafi's former interior minister, and two colonels also killed in the alleged ambush have not been found.

The news comes amid reports that US senator and former presidential candidate John McCain warned rebels to investigate human rights abuses or risk alienating their country from Washington. The Independent reported McCain as saying:

"I urge you to investigate recently documented abuses, hold people accountable as necessary, and ensure that opposition military forces are abiding by the principles of justice and human rights...

"As you surely know, the critics of the TNC, both in the United States and across the world, are eager to seize on any transgression to stoke opposition to the Council and to the Libyan people's fight for freedom."