Former US police officer Derek Chauvin has been convicted of murder and manslaughter in the death of African-American man George Floyd in a case that shocked the US, laying bare deep racial divisions.

Chauvin had pleaded not guilty to three charges of second-degree murder, third-degree murder and second-degree manslaughter.

A racially diverse jury of seven women and five men in the midwestern city of Minneapolis took less than two days at the end of a three-week trial to find the white officer guilty in unanimous decisions on all three charges he faced.

Chauvin, 45, could be handed decades behind bars for Mr Floyd's killing on 25 May last year.

Mr Floyd's death sparked protests against racial injustice around the world and is being seen as a landmark test of police accountability.

George Floyd

In an arrest captured on video, Mr Chauvin pushed his knee into the neck of Mr Floyd, who was handcuffed, for more than nine minutes outside the grocery shop where Mr Floyd had been accused of buying cigarettes with a fake $20 note.

The 12 sequestered jurors considered three weeks of testimony from 45 witnesses, including bystanders, police officials and medical experts, along with hours of video evidence in the most high-profile US case involving accusations of police misconduct in decades.

Chauvin, wearing a grey suit with a blue tie and white shirt as well as a light-blue facemask, nodded and stood quickly when the judge ruled that his bail was revoked.

He was taken out of the courtroom in handcuffs and placed in the custody of the Hennepin County Sheriff.

Derek Chauvin, right, pictured in the court yesterday

The case hinged on whether the jury believed the prosecution argument that Mr Chauvin used excessive, and therefore illegal, force that killed Mr Floyd.

The defence had countered that Mr Chauvin behaved as any "reasonable police officer" would, and sought to raise doubts about the cause of Mr Floyd's death, saying heart disease or even the exhaust fumes from the nearby police car may have been factors.

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Key moments in Derek Chauvin trial

The jury was comprised of four white women, two white men, three black men, one black woman and two multiracial women, according to court records.

The court has promised to shield their identities until some time after the verdict. Hennepin County District Judge Peter Cahill presided over the trial.

Floyd family lawyer Ben Crump hailed the verdict as a landmark victory for civil rights that could be a springboard to legislation to reform police forces in their dealings with minorities.

"Painfully earned justice has finally arrived for George Floyd's family. This verdict is a turning point in history and sends a clear message on the need for accountability of law enforcement," Mr Crump tweeted.

"Justice for Black America is justice for all of America!"

Outside the courthouse, a crowd of several hundred people erupted in cheers when the verdict was announced.

Chants of "George Floyd" and "All three counts" broke out. At George Floyd square in Minneapolis, the intersection where Mr Floyd was killed and is now named after him, people screamed, applauded and wept.

The site has since become a rallying point for racial justice protests.

People react outside court
People celebrate outside the court in Minneapolis after the verdict is announced

US President Joe Biden spoke with Mr Floyd's family yesterday "to check in with them and also share that the family was in his prayers", White House Press Secretary Jen Psaki said.

Earlier, Mr Biden had called for the "right" verdict in the trial.

"I'm praying the verdict is the right verdict. I think (it's)... overwhelming in my view," Mr Biden told reporters, noting that he was only speaking openly because the jury has been sequestered.

Mr Biden said the Floyd family were feeling "pressure and anxiety".

Hennepin court
A Sheriff's vehicle enters the Hennepin County Government Centre where the court sat in Minneapolis

The courtroom drama played out before the eyes of the US as Daunte Wright, a 20-year-old black man, was shot dead in a Minneapolis suburb by a white policewoman who apparently mistook her gun for her Taser, and a 13-year-old boy who was killed by police in Chicago.

Mr Wright's killing triggered several nights of protests in Minneapolis, and ahead of the verdict in Chauvin's case, National Guard troops were deployed in the Minnesota city.

The courthouse was surrounded by high barricades and many downtown businesses boarded up their windows for fear of a repeat of the violent street clashes that unfolded last year between police in riot gear and protesters.

Three other former police officers - Tou Thao, Thomas Lane, and J. Alexander Kueng - also face charges in connection with Mr Floyd's death.

They are to be tried separately later in the year.