Bin Laden death: Security fears for US Navy Seal team

Mr Gates revealed that the US Navy Seal team had expressed concerns over their safety and that of their families.

Al-Qaeda has vowed to avenge the death of its leader in the helicopter-borne raid on his compound in Abbottabad, northern Pakistan.

Mr Gates said threats against US forces had increased since Bin Laden's death.

The defence secretary, addressing US marines at Camp Lejeune in North Carolina, said he had met the Seal team last week and they raised the issue of their security "and particularly with respect to their families".

"We are looking at what measures can be taken to pump up the security," he said.

"As a result, there has been a consistent and effective effort to protect the identities of those who participated in the raid. I think that has to continue," he added.