WASHINGTON (AFP) - The White House on Monday (Oct 31) opted for caution in reacting to FBI director James Comey's bombshell decision to announce further investigation of Mrs Hillary Clinton's e-mail days before the 2016 presidential election.

Spokesman Josh Earnest said he would "neither defend nor criticise" Mr Comey, who has been blasted by Democrats since last Friday.

Mr Earnest said President Barack Obama considered Mr Comey - a Republican appointee - to be "a man of integrity, a man of principle and he's a man of good character".

But he also pointed to norms that "limit public discussion of facts that are collected in the context" of ongoing investigations.

"The President believes that it's important for those norms and traditions and guidelines to be followed," the spokesman said.

Mr Earnest said that Mr Obama did not share the view of some Democrats who have suggested that Mr Comey was seeking to tilt the vote in favour of Republican Donald Trump through the new revelations.

"The President doesn't believe that director Comey is intentionally trying to influence the outcome of an election," Mr Earnest said. "The President doesn't believe that he's secretly strategising to benefit one candidate or one political party."

Mr Earnest did, however, acknowledge the intensity of criticism facing Mr Comey, from all quarters.

"He's in a tough spot, and he's the one who will be in a position to defend his actions in the face of significant criticism from a variety of legal experts, including individuals who served in senior Department of Justice positions in administrations led by presidents in both parties."

"But I'll neither defend nor criticise what director Comey has decided to communicate to the public about this investigation," he added.