WASHINGTON (AFP) - Former US deputy national security adviser K.T. McFarland withdrew her nomination to be ambassador to Singapore, in a move that left President Donald Trump "disappointed."

Ms McFarland's nomination proved controversial as senators questioned whether she knew about conversations between Russia's ambassador to Washington Sergey Kislyak and former national security adviser Michael Flynn in 2016.

Flynn pleaded guilty to lying to the FBI about those discussions in December, having been fired by Mr Trump over the matter months earlier.

Ms McFarland was nominated for the ambassador role after stepping down from her national security post following the arrival of Flynn's successor, General H.R. McMaster.

The nomination, put forward in May, was returned by the Senate to the White House early last month - only for Ms McFarland to be re-nominated a week later.

In a statement released on Friday (Feb 2), the President said Ms McFarland, also a former Fox News analyst, served the administration "with distinction" - but accused Democrats of choosing "to play politics rather than move forward with a qualified nominee for a critically important post".

"I wish K.T. the best as she uses her considerable wisdom and skill as a commentator to explain to the American people how to make American foreign policy great again," Mr Trump added.