CHICAGO • A white Ohio police officer who shot a black man during a routine traffic stop has been charged with murder in what prosecutors called a "senseless" act motivated by anger.

The case comes as the United States grapples with heightened racial tensions in the wake of a series of high-profile incidents of unarmed African Americans being killed by police officers in disputed circumstances.

"He wasn't dealing with someone who was wanted for murder - he was dealing with someone with a missing licence plate," Hamilton county prosecutor Joseph Deters told reporters.

"This is in the vernacular a pretty 'chicken crap' stop. If he started rolling away, seriously, let him go. You don't have to shoot him in the head."

University of Cincinnati campus police officer Ray Tensing initially told investigators that he shot Mr Sam DuBose in the head after Mr DuBose had tried to drive away and dragged the officer along with him.

But a review of the officer's body camera footage showed that Tensing was never in danger during the July 19 incident.

The university shut down its campus and placed barricades at entrances in concern over possible violent protests as have been seen in response to other high-profile police shootings in the past year.

City officials pressed for calm and said they were prepared "for any scenarios that present themselves". Despite concerns, there was no eruption of violent protests.

A small group of marchers gathered, waving "Black Lives Matter" placards, in reference to the grassroots movement opposing violence by law enforcement officers against blacks. One sign read: "They kill our daddies, then make fun of us for being fatherless."

Mr Deters said he hoped the swift action by his office would show that justice was being done.

"I feel so sorry for his family and I feel sorry for the community," he said, referring to the victim.

AGENCE FRANCE-PRESSE