Nikki Haley has said rumours that she is having an affair with Donald Trump are "highly offensive" and "disgusting".

Ms Haley, the US ambassador to the UN, said the reports were symptomatic of the attacks powerful women frequently encounter.

Rumours of a tryst between Ms Haley and the US president circulated after comments made by Michael Wolff, the author of an explosive book on life within the White House.

Wolff told an American TV network that he was “absolutely sure” Mr Trump is having an extramarital affair, but said he omitted the claim from his book, Fire and Fury, because he was not able to substantiate it.