A US federal investigation has been launched into policing practices in the city of Minneapolis, a day after one of its former officers was convicted of the murder of George Floyd. The justice department will look at whether there has been a pattern "of unconstitutional or unlawful policing", Attorney General Merrick Garland said.

It follows national outrage over the killing of Mr Floyd by Derek Chauvin. The former officer was convicted of all charges against him on Tuesday.

Chauvin was filmed kneeling on Mr Floyd's neck for more than nine minutes during an arrest in May 2020. Mr Floyd, an unarmed African American, was pronounced dead an hour later. His death sparked protests across the US and worldwide, and calls for police reform.

Tuesday's verdict has been widely welcomed in a country where police are rarely convicted - if they are charged at all - over deaths which occur in custody. But Mr Garland told reporters that he knew the verdict would not "address potentially systemic policing issues in Minneapolis".

The attorney general said the investigation would "include a comprehensive review of the Minneapolis Police Department's policies, training, supervision and use-of-force investigations." It will also examine "whether its treatment of those with behavioural health disabilities is unlawful", while looking at the "effectiveness of current systems of accountability and whether other mechanisms are needed to ensure constitutional and lawful policing."

Mr Garland said both the community and law enforcement would have to take part if the investigation were to be a success, and he had already started reaching out to both. If unlawful patterns or practices were found, he promised to issue a public report and bring a civil lawsuit.