The president was visiting the Walter Reed military hospital outside Washington, where he met wounded soldiers and health care workers.

“I’ve never been against masks but I do believe they have a time and a place,” he said as he left the White House.

He has previously said that he would not wear a mask and mocked Democratic rival Joe Biden for doing so.

But on Saturday he said: “I think when you’re in a hospital, especially in that particular setting, where you’re talking to a lot of soldiers and people that, in some cases, just got off the operating tables, I think it’s a great thing to wear a mask.

The change of tone came as the US recorded 66,528 coronavirus cases on Saturday, a new daily record.