Clarence House, the official residence of the Prince and his wife Camilla, Duchess of Cornwall.
Trump and Charles, heir to the throne throne, are expected to meet at the Clarence House Queen Elizabeth II, visiting leaders do not get a one-on-one with Charles.
Charles warned against "potential catastrophic global warming" in a speech during a tour of the Caribbean in March. "We demand the world's decision-makers take responsibility and solve this crisis," he said. The trump administration, by contrast, has been accused of deprioritizing the issue, withdrawing from the Paris climate accords in 201
The most likely date for the Trump-Charles encounter is June 3, the first day of the US President's visit. According to tradition, a state banquet, hosted by Queen Elizabeth, wants to take place on the first evening.
It's unclear whether the meeting took place at the Downing Street, which the Prince's office, or the White House.
Downing Street declined to comment, saying it was a matter for the Palace. CNN has sought comment from the White House.
A political prince
In the past, Charles has come under fire for testing the boundaries of the custom that British royals stay out of politics.
Trump's meeting with Charles wants to be the first since being elected. They previously met during a 2005 tour of the US by Charles and Camilla.
It was promptly released in London, including a 20-foot "trump baby" blimp that flop over the UK Parliament.
The two men have verbally sparred frequently and last week Khan said he did not see a reason to roll out the red carpet.
Max Foster reported and Sheena McKenzie wrote from London.