US Vice President Joe Biden, preparing for a possible presidential bid, on Tuesday sought to shield himself from potential criticism by Democratic frontrunner Hillary Clinton by saying he had supported the raid that killed former al Qaeda leader Osama bin Laden.

Mr Biden, who has said previously he advised President Barack Obama against approving the raid without making an additional attempt to verify bin Laden was present at the compound where he was eventually found, said on Monday he told the president privately to proceed.

"As we walked out of the room and walked upstairs, I said - I told him my opinion that I thought he should go, but follow his own instincts," Mr Biden told an event at the George Washington University.

Mr Obama has said previously that Mr Biden was not in favor of the raid on the compound in Pakistan that became one of the Democratic president's top foreign policy achievements. Mrs Clinton, who was secretary of state at the time, has highlighted her support for the raid.

The White House declined to weigh in on whether Mr Biden had changed his story about his position on the bin Laden move.

Mr Biden has said previously that he urged Mr Obama to follow his instincts on the matter.