Supergrasses are to protected by a national body by the first time after ministers conceded that the present system had failed to prevent the intimidation and even murder of key witnesses.

The UK Protected Person's Service, announced today, is designed to plug gaps in a witness protection system that the Ministry of Justice admits is currently "inconsistent, variable and lacking uniform standards of delivery".

The new service will aim to ensure that witnesses are less isolated, as well as improving communication between services in different parts of the country

One supergrass, responsible for jailing an international gang of drug dealers and robbers, told The Independent that two attempts on his life were made in prison after his photograph was released following his trial.

"I was sent to prison under my own name," he said. "My witness protection team have been fantastic. It wasn't their fault. But they are based hundreds of miles from where I live."

Earlier this year a 16-year-old boy was paid £600,000 compensation after his details were passed to a violent gang he was giving evidence against.

In 2004, the Lincolnshire couple Joan and John Stirland were shot dead in retaliation after Ms Stirland's son Michael O'Brien shot the nephew of a gangster. It is thought a telephone worker gave away their address.

And in February, the Leveson Inquiry was told that the News of the World had details of people on the current witness protection scheme.

Police and the Ministry of Justice say witness protection is essential for convicting the most violent criminals. The killer of school boy Rhys Jones, 11, shot in Liverpool in 2007, and the gangmaster responsible for the Morecambe Bay disaster in 2004 were convicted because witnesses were protected. There are currently between 2,000 and 3,000 witnesses in protection at a cost of £19m, the MoJ says.

But last year more than a quarter – 27 per cent – of collapsed prosecutions were due to the failure of witnesses or victims to give evidence.

The new body will come into force next December, under the auspices of the new National Crime Agency, and follows a review of witness protection service by senior police officers.

Assistant Chief Constable Andy Cooke, of the Association of Chief Police Officers, who led the review, said the new body would "strengthen the fight against organised crime".

He said after the review last year: "We had a patchwork response across the country where levels of protection differed. Witness protection is underused and if there was a national service people would be encouraged to use it."

Victims minister Helen Grant said: "The UK Protected Persons Service will ensure those in need receive the expert protection and support no matter wherever they are in the UK."

Life as a supergrass: 'I can sleep at night'

Paul said he turned supergrass after being consumed by guilt for his role as the inside man in a multimillion-pound robbery. "I realised that I'd helped this gang go on to bigger things and they became international," he said. "When you're dealing drugs at that level people get hurt.

"I was paranoid, I'd had two heart attacks through drug use and when I cleaned myself up I couldn't live with myself. So I went to the police."

Two attempts were made on his life while he was in prison because his identity was leaked. "For a while the witness protection team are your only friends," he said. "It's a military operation to see your family. But I can sleep at night."