A grand jury in the US state of Ohio has declined to bring criminal charges against police officers involved in the fatal shooting last year of a 12-year-old boy in Cleveland, a prosecutor said Monday.

The November 2014 death of Tamir Rice -- who had been carrying a replica gun in a playground when he was shot dead -- and the fatal shooting of other African Americans by police triggered protests across the country.

"Based on the evidence they heard and the law as it applies to police use of deadly force, the grand jury declined to bring criminal charges," against the two officers involved, including the one who shot Rice, Tim McGinty, the prosecutor for Cuyahoga County, Ohio, told reporters.