New York City police chief Bill Bratton to step down

Bill Bratton and New York Mayor Bill de Blasio

New York City Police Commissioner Bill Bratton - the most prominent law enforcement officer in the US - will step down in September.

Mayor Bill de Blasio announced Mr Bratton's retirement on Tuesday, saying his accomplishments were "inestimable and extraordinary".

Mr Bratton, 68, had previously said he would not serve after 2017.

Protesters linked to the Black Lives Matter group had called for him to be fired.

On Monday more than 100 people gathered at a New York rally to protest against what they said was racial bias by the police.

Mr Bratton previously led police departments in Boston and Los Angeles. He also ran the New York Police Department from 1994 to 1996 under then-Mayor Rudy Giuliani.

He is known for his aggressive efforts to combat crime in the 1990s, in accordance with "broken windows theory", which advocates dealing strongly with low-level anti-social behaviour as a way to prevent more serious crime.

He was given the moniker "Supercop" when he helped UK police after riots five years ago.

Mr Bratton was a strong opponent of the stop-and-frisk tactics used by his predecessor, which he said unfairly targeted black and Hispanic people.

But his "broken windows" policy attracted criticism.

In December 2014, an unarmed black man, Eric Garner, was confronted by police while allegedly selling stolen cigarettes. He died in a policeman's chokehold. The white officer, Daniel Pantaleo, was not indicted.

The NYPD's top uniformed officer, Chief James O'Neill, will replace Mr Bratton.

Mr O'Neill, who like Mr Bratton is white, has worked for the NYPD for 30 years and was instrumental in building its neighbourhood policing programme.

Mr Bratton welcomed his successor's appointment, saying: "Jim O'Neill's acumen as a tough cop was honed in the subways, the streets, and later running precincts, narcotics and fugitive apprehension.

"Few understand the human side of policing better than Jim O'Neill."

Mr de Blasio said: "We will never forget or fail to honour the achievements of Bill Bratton."