President Donald Trump has made his first public appearance since returning to the White House following treatment for coronavirus.

Beginning his address, President Trump gave thanks to those who'd said a prayer for his recovery: "I want to thank all of you for your prayers, I know you've been praying."

The president wore a mask as he walked out for the speech but took it off to make his remarks. He received an enthusiastic response from his supporters.

Donald Trump's doctor has said the President's no longer at risk of transmitting Covid-19. 

Sean Conley said the US president meets the criteria to safely come out of isolation - with three weeks to go until election day. 

President Trump delivered an address on his support for law enforcement from the Blue Room balcony to a friendly crowd.

The president is also priming for a Florida rally on Monday and campaign events in Iowa and Pennsylvania later in the week.

The White House insisted the event on the South Lawn was an official event and not a campaign rally. But President Trump used the address to make broadsides against the Democratic ticket of former vice president Joe Biden and Senator Kamala Harris.

"I think we're gonna swamp them by so much," he said.

President Trump appeared healthy, though perhaps a little hoarse, during the 18-minute speech that was intended to send the message that he is back and ready to resume his battle for re-election.

Security was stepped up around the White House before the event, which was called a "peaceful protest for law and order".

Police and the Secret Service closed surrounding streets to vehicles and shut down Lafayette Square, the park near the White House that has long been a gathering place for public protest.