LONDON — The leader of the world's Anglicans, Archbishop of Canterbury Rowan Williams, said on Thursday he felt "very uncomfortable" over the killing of Osama bin Laden while unarmed.

Williams also criticised the conflicting versions that American officials have given of the Al-Qaeda leader's death in a US commando raid on his compound in Abbottabad, Pakistan on Sunday.

"I think the killing of an unarmed man is always going to leave a very uncomfortable feeling because it doesn't look as if justice is seen to be done," Williams said at a press briefing when asked about bin Laden's death.

"In those circumstances I think it's also true that the different versions of events that have emerged in recent days have not done a great deal to help," he added.

US Attorney General Eric Holder on Wednesday defended the legality of the special forces swoop after it emerged bin Laden was unarmed when he was gunned down, saying there was no indication he attempted to surrender.

But Williams said that justice should be seen to be done.

"I don't know the full details any more than anyone else does. But I do believe that in such circumstances when we are faced with someone who was manifestly a war criminal in terms of the atrocities inflicted it is important that justice is seen to be served," the archbishop said.

The comments by Williams came as UN human rights chief Navi Pillay called for "a full disclosure of the accurate facts" to determine the legality of the killing of bin Laden.