WASHINGTON (AFP) - The White House said on Thursday (May 24) that a North Korean failure to keep its word had led US President Donald Trump to call off his summit with Kim Jong Un next month.

"There has been a trail of broken promises that gave the United States pause," said a senior White House official, speaking on condition of anonymity.

"President Trump is willing to pursue diplomacy as far as it can be possibly pursued," added the official - who said the US leader had "dictated every word" of his letter to Kim cancelling the June 12 summit.

Pointing at what it called a "profound lack of good faith," the official said Pyongyang failed to turn up to a preparatory meeting in Singapore with the White House deputy chief of staff.

"They waited and they waited. The North Koreans never showed up. The North Koreans did not tell us anything - they simply stood us up," the official said.

The White House also views North Korea's objection to a routine US-South Korean joint military exercise - and its cancellation of a meeting with the South Koreans - as a breach of its commitments leading up to the summit.

"That constituted a broken promise," the official said.

Trump announced the cancellation of the talks shortly after North Korea declared it had "completely" dismantled its nuclear test site, a move portrayed as a goodwill gesture ahead of the landmark Trump-Kim talks.

The White House official said North Korea's failure to allow international observers to verify the dismantling had further eroded trust.

US officials "were promised by the North Koreans that international experts and officials would be invited to witness and verify today's demolition.

"But that promise was broken. Instead journalists were invited and we will not have forensic evidence that much was accomplished," the official said.

"We certainly hope that's it's the case but really don't know."