US taking 9/11 threat seriously: Biden

US Vice President Joe Biden said Friday the administration was taking seriously a credible but unconfirmed terror threat surrounding the 10th anniversary of the 9/11 attack.

"This is the first, the first credible piece of information we've gotten," Biden said on NBC's Today programme. "We cannot confirm it. We are doing everything within our power. All hands are on deck," he said.

Officials earlier said there was a "specific, credible but unconfirmed" terror threat surrounding the 10th anniversary of the September 11, 2001, terror attacks.

At least three individuals intend to launch a vehicle-borne attack in Washington or New York as the 9/11 anniversary approaches, the officials said.

Biden said the White House was not able to confirm who those individuals might be, "but we are taking it seriously.”

Asked about what Americans should do when faced with such a threat, Biden advised people to continue their lives as normal, but to be vigilant and report anything that may look suspicious.

White House press secretary Jay Carney said President Barack Obama has been briefed about the threat and the administration was "hyper-vigilant" against it.