The BBC's Richard Hannaford reports

The Big Issue in the North Trust interviewed 560 users of "hard drugs" and 120 GPs, who delivered a damning verdict on the success of specialist drug services in the north-west of England.

The Big Issue is a weekly newspaper that campaigns on behalf of homeless people and aims to highlight major social issues.

The researchers found that a third of those still taking drugs had been in contact with the people supposed to help them quit for more than five years - and one in eight had been in contact for more than a decade.

Methadone 'not failing'

In addition, 44% of those prescribed heroin substitute methadone were still using heroin on a daily basis, and over 80% on methadone were using some form of street drugs on at least a weekly basis.

Drugs Tsar Keith Hellawell: "The government's methadone programme is not failing"

But government drugs chief Keith Hellawell, speaking on BBC Two's Newsnight programme, defended the effectiveness of methadone, and said it was "not failing".

Describing it as a "maintenance programme", he said its use for drug addicts was laid out in his annual strategy and in the targets set by the government during the next 10 years.

He said it was investing heavily in its drugs programme, and that the money would be used for both treatment and prevention.

Many users are taking methadone and illegal drugs

But he conceded that there was a "shortage of detoxification places in the UK". Manchester has only three-and-a-half beds available, and he said the extra money was aimed at remedying this.

Ann McNamara, the chairwoman of the Big Issue in the North Trust, said: "This isn't about 'drug users' alone - if left unchecked, failing drugs services will have an effect on all of us when it comes to crime, social welfare, health and tax.

"This report shows that the services designed to solve the problems are just not good enough."

The charity is calling for the introduction of quality standards on a local, regional and national level so services can be monitored, and targets set for drugs services.

Other statistics from the report include:

• 17% of those on methadone are injecting heroin and not using needle exchanges
• Only 11% were working, and more than half had lost regular contact with their children
• The most frequent services used were for methadone prescriptions
• GPs felt that stimulant users (eg crack, cocaine and amphetamines) were not well catered for
• Only a quarter of those questioned had received some form of counselling

However, leading national drugs charity the Standing Conference on Drug Abuse said that standards were already improving.

Chief Executive Roger Howard said: "We recognise there is much room for improvement in the standard of drug treatment and care.

"However we should not forget that appropriate methadone maintenance programmes are very beneficial to many drug misusers."

He added: "We are still at the early stages of a 10-year government drug strategy but many of the problems raised by the Big Issue are starting to be tackled."

The government says it has set aside £217m for its anti-drugs programme, but this is divided up between different departments, including education, prevention, treatment and crime-fighting.