Amid the pomp and formality of the first White House visit by the British royalty since 2007, President Donald Trump joked about his marriage not lasting as long as his parents' 63-year union and said his mother had a crush on King Charles III.

Trump addressed the crowd gathered on the White House South Lawn from a stage with the king, Queen Camilla and the first lady, recounting his mother's Scottish heritage and her love for the British royals.

The president said his mother was "glued to the television" when an event with Queen Elizabeth II, King Charles' mother, was being shown.

"She'd say, 'Look Donald, look how beautiful that is.' She really did love the family," Trump said. "But I also remember her saying, very clearly, 'Charles, look, young Charles, he's so cute.'"

Trump turned to the king and said "That's my mother," prompting the monarch to nod and wave his hand at the president.