Donald Trump 'spoke from Air Force One to prank caller for almost four minutes, didn't realise'

A podcaster says he spoke on the phone to US President Donald Trump on Air Force One for almost four minutes by pretending to be a Democratic senator — and the President did not realise.

A voice purportedly belonging to Mr Trump discussed topics including immigration in the phone call with John "Stuttering John" Melendez, who pretended to be Senator Bob Menendez.

The recording was included in an episode of Melendez's Stuttering John Podcast.

Melendez, a comedian known for his time on the Howard Stern Show, said he was first put through to Mr Trump's son-in-law and senior adviser Jared Kushner, who asked him what he wanted to talk to the President about.

After he told him he wanted to discuss immigration, Melendez said Mr Kushner responded: "OK, cool, I'll tell him."

He said he was "shocked" Mr Trump then returned his call — from his plane.

"Hi, Bob. Congratulations on everything. We're proud of you. Congratulations, great job," Mr Trump purportedly began the conversation.

"You went through a tough, tough situation and I don't think a very fair situation, but congratulations."

He did not specify what he was referring to, but New Jersey's Senator Menendez recently won his primary contest, after a hung jury spared him a conviction in a federal bribery case last year.

Republicans are reportedly pleased about his win and hope to use his legal troubles to tar other Democrats.