By late on Saturday, the White House was yet to confirmed that the dinner had taken place.

Warmbier's parents, Fred and Cindy Warmbier say their son was tortured in prison.

They were angered by Trump's comments last spring that he took North Korean leader Kim Jong Un "at his word" that he was unaware of any mistreatment of their son.

Trump later tweeted, "Of course I hold North Korea responsible for Otto's mistreatment and death." The tweet made no mention of Kim, with whom Trump is pursuing nuclear talks.

Doctors in Cincinnati said Warmbier had suffered severe brain damage, although they weren't sure what led to it.

North Korea denied mistreating him, saying he fell into a coma that resulted from botulism and a sleeping pill.

A law firm representing the Warmbier family didn't immediately respond to a request for comment.

AP