LONDON: The US commando raid that killed Osama bin Laden was "not an assassination", US Attorney General Eric Holder said Thursday after the al Qaeda leader's sons denounced the operation.

Holder told the BBC the raid on bin Laden's hideout in Pakistan on May 2 was a "kill or capture mission" and that his surrender would have been accepted if offered, but that the safety of US Navy commandos was paramount.

"What happened to bin Laden was not an assassination," Holder said.

"I think the action that we took against him can be seen as an act of national self-defence. You have to remember it is lawful to target an enemy commander," he said.

The top US legal official said there was no indication that bin Laden was going to surrender and it was believed he could be wearing a suicide vest.

"It was a kill or capture mission. If there was a possibility of a feasible surrender that would have occurred, but their protection, that is the protection of the force that went into the compound, was uppermost in their minds," said Holder.

"This is a man who swore he would never be taken alive. There were some indications that perhaps he wore a suicide vest, there's indications that perhaps there were weapons in the room." Bin Laden's body was buried at sea hours after the operation in which US special forces in helicopters flew under Pakistani radar cover and raided a house in the northwestern garrison town of Abbottabad.

Bin Laden's sons on Tuesday denounced his "arbitrary killing" and burial at sea.

In a statement given to the New York Times, the sons asked why their father "was not arrested and tried in a court of law so that the truth is revealed to the people of the world."