Infamous gangster James "Whitey" Bulger has died in a US prison.

His body was discovered wrapped in a sheet after he failed to turn up for breakfast on Tuesday.

Reuters reported that the 89-year-old had been so badly beaten he was bleeding from his ears.

A prison employee, who has not been named, told the news agency that CCTV images show two men entered Bulger's cell less than 24 hours after he arrived at the jail in a wheelchair.

The New York Times said Bulger had been "beaten unrecognisable".

Once one of America's most wanted fugitives, Bulger was jailed in 2013 for being complicit in 11 murders.

His conviction followed 16 years on the run and his notoriety inspired several movies.

Jack Nicholson's character in The Departed was based on the career criminal, and he was played by Johnny Depp in the biographical film Black Mass.

The FBI has confirmed it is investigating the death, which a prison official said is being treated as murder.

Officials have not given a cause of death.

The Bureau of Prisons said no other inmates or staff were injured.

Bulger was reportedly moved to the Hazelton prison after spending only a week in an Oklahoma jail.

He had been moved there from a prison in Florida.

It is not known why Bulger had been forced to change jails so often recently.

Bulger was one of Boston's underworld bosses, and led the Winter Hill Gang that ran loan-sharking, gambling and drug rackets in the Boston area.

The mob boss lived a double life as an FBI informant.

The gangster became one of the FBI's "Top Ten Most Wanted Men" after he fled Boston in 1994.

Mr Connolly Jr had informed him that he was going to indicted.

Bulger spent 16 years as a fugitive before he was caught in Santa Monica, California, in 2011.

Bulger was sentenced to two consecutive life terms plus five years for 11 murders, plus other charges including racketeering.