'Do you know who this is?' - US President Donald Trump on Boris Johnson

US President Donald Trump has made it quite clear what he thinks of UK Prime Minister Boris Johnson.

"Do you know who this is? Does everybody know?" Trump asked reporters as he introduced Johnson at a G7 summit in France on Sunday (local time).

"He's going to be a fantastic Prime Minister, I can tell you."

Brexit Britain will have a major trade deal with the US, Trump told Johnson on Sunday (local time), adding that the new British Prime Minister was the right man to take his country out of the European Union.

"We're having very, very good meetings," Trump said. "So far it's been very good."

Johnson, who faces a delicate task keeping European allies on side whilst not angering Trump at the G7 summit, said trade talks with the US would be tough but there were huge opportunities for British businesses in the US market.

"We're going to do a fantastic deal," Johnson said. "Once we clear up some of the obstacles in our path."

Asked what his advice was for Brexit before going into a bilateral meeting with Johnson on the summit sidelines, Trump said: "He needs no advice, he is the right man for the job."

Reuters/Newshub.