Four Minneapolis police officers who were involved in the arrest of a black man who died in police custody have been fired hours after a bystander’s video showed the man pleading that he could not breathe as a white officer knelt on his neck.

Minneapolis Mayor Jacob Frey tweeted about the firings, saying: “This is the right call.”

The man’s on death Monday night after he struggled with officers is under investigation by the FBI and state law enforcement authorities.

Minneapolis Mayor Jacob Frey apologised to the black community on Tuesday in a post on his Facebook page.

“Being Black in America should not be a death sentence. For five minutes, we watched a white officer press his knee into a Black man’s neck. Five minutes. When you hear someone calling for help, you’re supposed to help. This officer failed in the most basic, human sense,” Mr Frey posted.

Police said the man matched the description of a suspect in a forgery case at a grocery store, and that he resisted arrest. The unidentified officer ignores his pleas. “Please, please, please, I can’t breathe. Please, man”. the man is heard telling the officer.

After several minutes, one of the officers tells the man to “relax.” Minutes pass, and the man becomes motionless under the officer’s restraint. The officer leaves his knee on the man’s neck for several minutes more.

Several witnesses had gathered on a nearby pavement, some recording the scene on their phones. The bystanders became increasingly agitated as the man pleaded with police. One bystander told officers they need to let him breathe. Another yelled at them to check the man’s pulse.

The man who died was identified as George Floyd by Ben Crump, a prominent civil rights and personal injury lawyer who said he had been hired by Mr Floyd’s family.

“We all watched the horrific death of George Floyd on video as witnesses begged the police officer to take him into the police car and get off his neck,” Mr 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 about a non-violent charge.”

Minneapolis Police Chief Medaria Arradondo said the department would conduct a full internal investigation.

In Minneapolis, kneeling on a suspect’s neck is allowed under the department’s use-of-force policy for officers who have received training in how to compress a neck without applying direct pressure to the airway. It is considered a “non-deadly force option,” according to the department’s policy handbook.