Michael Brown was robbery suspect before being shot by Officer Darren Wilson

Michael Brown was a suspect in a robbery just moments earlier he was shot by police on Saturday in Ferguson, Missouri, police have said.

Michael Brown, 18, was one of two men suspected of robbing a nearby convenience store, police say.

Minutes later he was shot by Officer Darren Wilson after a struggle, Ferguson police Chief Thomas Jackson said on Friday.

The killing sparked days of violent protests in Ferguson.

Thomas Jackson described the robbery at the convenience store as being committed without the use of a weapon.

Police released to the press pictures of a well-built black man intimidating a clerk in the store.

The report identifies Michael Brown, who is described as being 6ft 4in and 292 pounds, as one of the robbers.

It says he “grabbed a box of Swisher Sweet cigars” and handed them to a second suspect identified as Michael Brown’s friend, Dorian Johnson.

Since the shooting on Saturday, Thomas Johnson has given a number of interviews in which he has said Michael Brown held up his hands in an act of surrender before being shot by the officer.

He has not mentioned his involvement in any robbery.

Darren Wilson, the police officer said to have shot Michael Brown, is a six-year veteran of the police force with no disciplinary record, Thomas Jackson said.

Thomas Jackson said he was treated for injuries sustained during the confrontation with Michael Brown, but he provided no other details of the deadly encounter.

Members of the majority black Ferguson community reacted angrily to the announcement that Michael Brown was a police suspect.

The revelations came after days of furious protests in Ferguson over the killing, to which police responded with tear gas and rubber bullets.

On Thursday night, tension seemed to ease, at least momentarily, as state police took charge of security.

Captain Ronald Johnson of the Missouri Highway Patrol, an African-American who grew up nearby, was named as the new head of the operation.

The previous evening, the reverberations from the Mid-west town were felt nationwide with dozens of vigils organized by a social media campaign.

The event in Washington DC was attended by hundreds of people in Malcolm X Park, many holding placards saying: “Hands up. Don’t shoot”.

Similar vigils were held in New York, Boston, Detroit, Chicago and many other cities.

They came at the end of a day when Missouri Governor Jay Nixon likened the scenes of violence in Ferguson to a “war zone” and the police conduct was questioned.

Attorney General Eric Holder said the use of military equipment and vehicles in Ferguson had sent a “conflicting message”, while President Barack Obama said there was no excuse for police using “excessive force”.

Barack Obama has promised a full investigation by the US Department of Justice into the teenager’s death, and the FBI has launched its own inquiry.