US President Barack Obama last night refused to release photographs of Osama bin Laden's body, believing it would incite violence and be used as an al Qaeda propaganda tool.

His decision came as the US forcefully defended its killing of the founder and leader of al Qaeda as an act of national self-defence after questions were raised about the legality of the secret operation involving Navy Seals in Pakistan.

US Attorney General Eric Holder told the Senate Judiciary Committee that the mastermind of the September 11 terror attacks had no intention of being captured by American forces who entered his compound in Abbottabad, north-west Pakistan.

Mr Obama believes that few credible people questioned the death and that conspiracy theorists would not be satisfied with a photo. He said: “You know, we don’t trot out this stuff as trophies.

“It is important for us to make sure that very graphic photos of somebody who was shot in the head are not floating around as an incitement to additional violence, as a propaganda tool. You know, that’s not who we are.

“The fact of the matter is, this was somebody who was deserving of the justice that he received. And I think Americans and people around the world are glad that he’s gone.

“But we don’t need to spike the football. And I think that given the graphic nature of these photos, it would create some national security risk.”

Asked about those who would say bin Laden’s death was just an American trick, he replied: “The truth is that, and we’re monitoring worldwide reaction, there’s no doubt that Bin Laden is dead. Certainly there’s no doubt among al Qaeda members that he is dead.

“And so we don’t think that a photograph ... of itself is going to make any difference. There are going be some folks who deny it. The fact of the matter is, you will not see bin Laden walking on this Earth again.”

Bin Laden was unarmed as he was shot twice in the head after special forces raided his compound in the town of Abbottabad on Monday. The secret mission was carried out without the knowledge of the Pakistani authorities.

Mr Holder said: “Let me make something very clear, the operation in which Osama bin Laden was killed was lawful. He was the head of al Qaeda, an organization that had conducted the attacks of September 11. He admitted his involvement.”

It was lawful to target bin Laden because he was the enemy commander in the field and the operation was consistent with US laws and values, he said, adding that it was a “kill or capture mission.”

“It was justified as an act of national self-defence,” Mr Holder said. “If he had surrendered, attempted to surrender, I think we should obviously have accepted that, but there was no indication that he wanted to do that and therefore his killing was appropriate.”

Dr Jonathan Eyal, Director of International Security Studies at the Royal United Services Institute in London said a strict interpretation of international law said the actions of the US in entering Pakistan to deal with bin Laden without the country’s permission made it illegal.

He did not believe the Americans would have wanted him alive, because of the “jungle” of legal ramifications in bringing him to trial.

Nato secretary-general Anders Fogh Rasmussen said the US operation was justified.

But former West German Chancellor Helmut Schmidt has said the killing was a violation of international law.

And British human rights lawyer Geoffrey Robertson QC said: “This man has been subject to summary execution, and what is now appearing after a good deal of disinformation from the White House is it may well have been a cold-blooded assassination.

“The last thing he wanted was to be put on trial, to be convicted and to end his life in a prison farm in upstate New York. What he wanted was exactly what he got – to be shot in mid-jihad and get a fast track to paradise.”

Bin Laden’s 12-year-old daughter has claimed that she watched as her father was captured alive and then shot dead by US special forces in front of his family.

Pakistani officials said earlier they alerted the US to suspicions about bin Laden’s compound in Abbottabad as far back as 2009.

The country’s foreign secretary Salman Bashir said American concerns over whether they could trust Pakistan’s security and intelligence services were misplaced and insisted it had extended every co-operation to the US and played a “pivotal role” in the fight against terror.

But the Afghanistan government escalated criticism of Pakistan by publicly questioning for the first time how its government could assure the security of its own nuclear weapons if it did not know the world’s most wanted terrorist had been hiding in a compound in a Pakistani military town less than an hour from the Pakistani capital.