US Defence Secretary Mark Esper speaks at a press conference. File photo

United States and South Korea are postponing a joint military air exercise that North Korea has criticised as provocative.

US Defence Secretary Mark Esper and his South Korean counterpart made the announcement Sunday in Bangkok, where they were attending an Asia defence ministers conference.

As recently as Friday, when Esper was in Seoul to consult with South Korean officials, there was no word on postponing the military air exercise, which had been called Vigilant Ace.

Seoul and Washington had scaled back the exercise recently and changed the name, but North Korea strongly objected, calling it evidence of a lack of interest in improving relations.

The North has demanded accommodations before it will agree to resume nuclear negotiations.