Furor in US after black man dies as policeman kneels on his neck

A video of a handcuffed black man dying while a Minneapolis officer knelt on his neck for more than five minutes sparked a fresh furor in the US over police treatment of African Americans Tuesday.

Minneapolis Mayor Jacob Frey fired four police officers following the death in custody of George Floyd on Monday as he was pressed shirtless onto a Minneapolis street, one officer's knee on his neck.

"Your knee in my neck. I can't breathe... Mama. Mama," Floyd pleaded.

Bystanders filmed the scene as Floyd slowly grew silent and motionless, unable to move even as the officers taunted him to "get up and get in the car."

Frey expressed outrage at the scene as calls rose for the officers to be prosecuted for murder.

"What I saw was wrong at every level," he said of the video.

"For five minutes, we watched as a white officer pressed his knee into the neck of a black man," Frey said.

"Being black in America should not be a death sentence."

Civil rights attorney Ben Crump said he had been retained by Floyd's family.

Floyd had been stopped by police for a forgery charge, Crump said in a statement.

"This abusive, excessive and inhumane use of force cost the life of a man who was being detained by the police for questioning on a non-violent charge," he said.

Floyd's death recalled the 2014 choking death of New Yorker Eric Garner by police, who was being detained for illegally selling cigarettes.

His death helped spark the nationwide Black Lives Matter movement.

Floyd's death comes on the heels of two other deaths of African-Americans that involved police wrongdoing.

On March 13 in Louisville, three white Kentucky policemen forced their way into the home of a black woman, Breonna Taylor, and shot her in a drug investigation.

And local police and prosecutors in Brunswick, Georgia allegedly covered up the killing of a young black jogger by the son of a retired investigator for local law enforcement.

The police allegedly withheld for two months a video showing Ahmaud Arbery, 25, being followed and then shot with a shotgun in broad daylight.

Arbery's family is also being represented by Crump.