The White House said on Monday Donald Trump had been referring to a call with South Korea's leader when he appeared to suggest a landmark direct contact with the nuclear North.

Mr Trump raised eyebrows at a Washington media dinner on Saturday when he said "they, by the way, called up a couple of days ago and said, 'we would like to talk'."

"And I said, 'so would we, but you have to de-nuke, you have to de-nuke'," Mr Trump added.

A senior administration official, speaking on condition of anonymity, told AFP Mr Trump had in fact been referencing a call he had on Thursday with South Korean President Moon Jae-in.

Pyongyang is the Korean peninsula's only nuclear-armed power, prompting speculation of rare direct contact between US and North Korean officials.

Mr Moon has prodded Mr Trump toward negotiations and has met North Korean officials himself.

Mr Trump has taken a more bellicose position, suggesting military action is possible if North Korea does not stop efforts to develop a nuclear-armed missile capable of hitting the continental United States.