The mayor of Atlanta, one of dozens of US cities hit by massive protests after the police killing of a black man, has warned demonstrators they have put themselves at risk of contracting coronavirus and should get tested.

As emergency orders imposed at the start of the pandemic are lifted and beaches and businesses reopen across America, protests have now been added to the list of concerns about a possible second wave of infections.

There are similar concerns in Paris and Hong Kong, where anti-government protesters have accused police of using social distancing rules to break up their rallies.

Health experts fear silent carriers of the virus who have no symptoms could unwittingly infect others at gatherings with people packed cheek to jowl and cheering and jeering, many without masks.

US protests
The large-scale protests make social distancing impossible (Mike Stewart/PA)

One protester said she has no choice but to demonstrate.

“It’s not okay that in the middle of a pandemic we have to be out here risking our lives,” Spence Ingram, a black woman, said after marching with other protesters to the state capitol in Atlanta on Friday.

“But I have to protest for my life and fight for my life all the time.”

Atlanta mayor Keisha Lance Bottoms, in her warning issued on Saturday evening, said: “There is still a pandemic in America that’s killing black and brown people at higher numbers.”

Minnesota governor Tim Walz said after another night of unrest in Minneapolis that many protesters wearing masks were simply trying to hide their identities and “cause confusion and take advantage of this situation”.

US protests
Many protesters have been wearing masks, but are not separating themselves from others (Nam Y Huh/AP)

The protests started in Minneapolis following the death there of George Floyd last Monday after a white police officer pressed a knee into his neck.

The state’s health commissioner has warned the protests are almost certain to fuel new cases of the virus.

Minnesota reported 35 coronavirus deaths on Thursday, a single-day high since the start of the outbreak, and 29 more on Friday.

“We have two crises that are sandwiched on top of one other,” Minneapolis mayor Jacob Frey said.

The US has been worst hit by the coronavirus outbreak, with more than 1.7 million cases and over 103,000 deaths.