US President Donald Trump has released a lengthy television interview ahead of its airing, a highly unusual move which he said was to expose the interviewer’s bias.

Mr Trump posted the nearly 40-minute sit-down with veteran journalist Lesley Stahl, of CBS‘s 60 Minutes program, to social media with the caption: “Look at the bias, hatred and rudeness on behalf of 60 Minutes and CBS.”

The president, appearing to be in a foul mood during the interview, repeatedly complains that he faces “tough questions” while his Democratic rival Joe Biden gets “softball” questions.

“Just be fair,” he tells Stahl at the beginning of the clip.

“I wish you would interview Joe Biden like you interview me.”

The media “discredited” itself by asking Biden about his favourite ice cream flavour, Mr Trump charged.

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The president also accuses the program of covering up for Mr Biden after the journalist tells him: “We can’t put on things we can’t verify.”

“We have enough,” Mr Trump says at the end of the clip, abruptly ending the interview and leaving before a scheduled walk-and-talk.

An interview Vice President Mike Pence did with 60 Minutes was also posted.

Trump has often accused the US media of being biased against him but releasing the interview prior to its Sunday airing is very unusual.

The president had already threatened on Tuesday to share the White House’s copy of the video interview early, “so that everybody can get a glimpse of what a FAKE and BIASED interview is all about”.

“The White House’s unprecedented decision to disregard their agreement with CBS News and release their footage will not deter 60 Minutes from providing its full, fair and contextual reporting,” the broadcaster said in a statement.

Mr Trump’s interview is supposed to be aired in a special package alongside a Biden interview.

60 Minutes is among the most-watched news shows on US television and is particularly popular among seniors.

-AAP