Susan Rice, the U.S. permanent representative to the UN, is to become President Barack Obama's national security adviser, officials say, according to BBC News.

She will replace Tom Donilon, who is set to announce shortly he is resigning after almost three years in the post. Samantha Power, an Obama adviser, will be nominated to replace her at the UN.

Rice was once seen as a contender for the job of secretary of state, but was forced to withdraw after opposition from Republicans in Congress. She was criticised for her remarks after an attack on diplomats in Libya.

On Wednesday, June 5 the White House said Obama would nominate Power, a human rights researcher and former White House adviser, to replace Rice as the U.S. ambassador to the United Nations.

Power, 42, left her White House adviser role earlier this year. Her nomination will require Senate approval. She was born in Ireland and wrote a Pulitzer-Prize winning book on America's foreign policy response to genocide.

The personnel shift comes as Obama prepares for a summit in California later this week with Chinese President Xi Jinping.

Rice, 48, dropped out of the running to be secretary of state under sustained Republican attack for her suggestion the armed assault on the U.S. compound in the city of Benghazi, Libya in September 2012 sprang from a spontaneous anti-American protest.