Donald Trump, the US president, has been accused of "shocking ignorance" after asserting that Korea "used to be a part of China" shortly after a meeting with Xi Jinping, the Chinese president.

Mr Trump made the comment in an interview with The Wall Street Journal on April 12, although the quote was only picked up on subsequently by the online news website Quartz.

In the interview, Mr Trump said of his Chinese counterpart, "Went into the history of China and Korea... And you know, you're talking about thousands of years ... and many wars. And Korea actually used to be a part of China".

The interview with the Journal was the same one in which Mr Trump revealed that the Chinese leader had explained the situation on the Korean Peninsula and he concluded, "After listening for 10 minutes, I realised it's not so easy".