U.S. President Barack Obama is to nominate John Brennan as the director of the Central Intelligence Agency, White House officials have said.

If confirmed, Mr Brennan will replace Gen David Petraeus, who resigned last year after admitting to an affair.

Chuck Hagel is to be put forward as the president's next defense secretary, replacing Leon Panetta.

Both appointments are expected to be formally announced later on Monday, Jan 7 and must be confirmed by the Senate.

Mr Brennan, a CIA veteran, is currently Mr Obama's chief counter-terrorism adviser. He was heavily involved in the planning of the 2011 raid that killed Osama bin Laden, BBC News reported.