Ex-police officer Derek Chauvin, sentenced to long imprisonment for the killing of African American George Floyd, has pleaded guilty for the first time in separate federal proceedings.

Chauvin admitted on Wednesday in federal court in Minneapolis, Minnesota, to have violated Floyd's civil rights, as reported in the US media.

In September, the 45-year-old had pleaded “not guilty”.

He changed this now in court.

The white policeman held the knee of Floyd, who was arrested and handcuffed on charges of counterfeit money, on May 25, 2020 in Minneapolis for around nine and a half minutes, although the 46-year-old black man repeatedly complained that he could no longer breathe.

Floyd's agonizing death, captured on a cell phone video, sparked international outrage and sparked national protests against racism and police violence.

Floyd's "I can't breathe" or "I can't breathe" complaint went around the world and became a motto of the anti-racism movement Black Lives Matter.

In June, Chauvin was sentenced to 22 years and six months in prison for second degree murder.

In parallel with the Minnesota State Justice, federal justice had also brought charges against Chauvin, as is possible in the United States.

She accuses the ex-cop of having violated Floyd's constitutional right not to suffer “disproportionate violence by a police officer”.

Chauvin faces 20 to 25 years imprisonment in the federal proceedings.

Both prison terms can be served at the same time.

According to media reports, the court had warned Chauvin that he could face life imprisonment without admission of guilt.

The ex-police officer also pleaded guilty on Wednesday of violating the civil rights of a 14-year-old, who he grabbed by the neck in 2017 and hit with a flashlight.