US President Donald Trump warned on Tuesday that the coronavirus crisis in the United States is likely to "get worse before it gets better."

"Some areas of our country are doing very well," Trump said at his first formal White House virus briefing since the end of April, according to AFP.

"Others are doing less well," the President continued. "It will probably unfortunately get worse before it gets better."

He said there had been "a concerning rise in (virus) cases in many parts of our South."

Trump urged Americans to wear facemasks to help prevent the spread of the highly contagious virus which has left more than 141,000 people dead in the United States.

"We are asking everybody that when you are not able to socially distance, wear a mask," he said.

"Whether you like the mask or not, they have an impact. They will have an effect and we need everything we can get," added Trump, who said the goal is "not merely to manage the pandemic but to end it."

"The vaccines are coming and they're coming a lot sooner than anyone thought possible," he said.

On Sunday, the US Centers for Disease Control and Prevention (CDC) reported 67,574 new coronavirus cases, taking the total to 3,698,161.

It said at the time the number of deaths had risen by 877 to 139,659.

Last Thursday, the United States reported at least 75,000 new COVID-19 cases, a record daily increase for the seventh time this month.

Though Trump has in the past said he would not wear a mask, earlier this month he was seen wearing a mask for the first time during a visit to the Walter Reed National Military Medical Center.

According to CNN, Trump's agreement to don a mask in public was the result of heavy "pleading" by aides, who urged the President to set an example for his supporters by wearing a mask on the visit.