Martin Luther King III accuses Minneapolis police officer of acting as 'judge, jury and executioner' over George Floyd's death

Human rights activist Martin Luther King III has accused the US police officer charged with the murder of George Floyd of acting as the "judge, jury and executioner".

Speaking after a sixth night of protests over Mr Floyd's death convulsed the United States, Mr King said he felt "great sadness and frustration" concerning the case.

"Mr George Floyd was murdered just a few days ago by police officers in this nation. He was murdered by police officers that we all watched as he was crying for help," Mr King, the son of rights leader Martin Luther King Jr, told BBC Radio 4's Today programme.

“The people that are supposed to protect and serve did nothing other than to allow one of their colleagues to continue to stand on his neck.

“Of course, what that says to me is the policeman who was supposed to protect and serve functioned as the judge, jury and the executioner."

Mr Floyd, 46, died on Monday after a video showed a white Minneapolis police officer kneeling on his neck for nearly nine minutes.

Police said Mr Floyd was reported on the evening of May 25 for allegedly using a counterfeit $20 bill at a grocery store.

Officers attending to the incident later found him sitting with two other people in a car parked around the corner from the store.

One of the four officers involved in the response pulled out his gun and ordered Mr Floyd to show his hands as he approached the car.

According to police, Mr Floyd then physically resisted officers as he was pulled from the car and handcuffed. Video of the incident does not show how the confrontation started.

Officer Derek Chauvin, 44,​ can be seen in footage of the incident with his knee on Mr Floyd's neck, while the latter can be heard saying "please, I can't breathe" and "don't kill me".

According to a preliminary autopsy by the county medical examiner, Mr Chauvin had his knee on Mr Floyd's neck for eight minutes and 46 seconds. Mr Floyd reportedly became non-responsive almost three minutes before Mr Chauvin removed his knee.

Mr Chauvin has since been charged with third-degree murder. The three other officers involved in Mr Floyd's arrest have not been charged, but have all been sacked.

The case has sparked demonstrations which have gripped cities from Philadelphia to Los Angeles, with the National Guard deployed in 15 states and authorities imposing dozens of curfews in response.

Police officers have fired tear gas and smoke bombs at demonstrators amid spates of looting and vandalism.

Mr King meanwhile told the BBC the Minneapolis Police Department's handling of the case had, in part, fuelled the widespread unrest prompted by Mr Floyd's death.

“I don’t think that the Minneapolis Police Department has helped itself because they have arrested one of the officers but they should have arrested all four of them," Mr King said.

"Had they done that, and charged them, some of this may not have happened.

He added: “Unfortunately, we have seen these kind of incidents happen in the African American community and by the hands of policemen over and over and over again.

“When is enough going to be enough? When our law enforcement people going to treat African Americans in the same way that everyone else should be treated?

“My father used to say violence is the language of the unheard. People’s voices have obviously not been heard because these kinds of things keep happening and keep happening."