A witness has told of the last harrowing minutes of George Floyd's life on the opening day of the trial of Derek Chauvin, the white American policeman accused of killing him.

Donald Williams III, a witness for the prosecution, said Mr Floyd was "slowly fading away" during the nine minutes Mr Chauvin kneeled on his back and neck.

Mr Chauvin's lawyer argued his use of force was "unattractive but necessary".

This trial is being seen by many as a pivotal moment in US race relations.

The May 2020 incident - in which Mr Chauvin was captured on video kneeling on the neck of Mr Floyd, who is black, in the city of Minneapolis - sparked protests in the US and across the world against police brutality and racism. Mr Chauvin, 45, who was dismissed from the police, denies murder and manslaughter charges, which carry sentences of up to 40 years in prison.

Three other officers present - Tou Thao, J Alexander Keung and Thomas Lane - will go on trial later in the year.