London: US President Donald Trump says he's not aware of any invitation for him to attend Prince Harry's wedding to Meghan Markle.

In a wide-ranging interview with Piers Morgan to be broadcast on Sunday in the UK, Trump replied "not that I know of" when asked if he had an invite to the May wedding.

Britain's Prince Harry and First Lady of the United States Melania Trump hold a bilateral meeting ahead of the start of the 2017 Invictus Games in Toronto, Canada. Credit:DANNY LAWSON

Markle has been a vocal critic of Trump, backing his rival Hillary Clinton and suggesting before the 2016 election she would leave the US if he won.

Asked if he would like to go to the royal wedding at Windsor Castle's St George's Chapel, Trump simply said: "I want them to be happy. I really want them to be happy."