Children as young as six have been treated for cannabis addiction, a drugs expert has said.

The revelation comes only days after a new study into the effects of cannabis led to calls for the Government to reclassify the drug.

Drugs counsellors in Greater Manchester reported children aged 11 and 12 regularly visited centres and a six-year-old had been referred for treatment.

A spokeswoman for the Oldham Alcohol Substance Intervention Service (Oasis) said children aged 14 most frequently arrived at the centre needing help and they had treated an eight-year-old.

The facility opened around five years ago and offers support to young people suffering drug abuse problems. A spokeswoman said: "It is very unusual to have a child as young as eight suffering from cannabis addiction. We have only had one case of a child of that age coming to use within the last five years. Alcohol, not cannabis, remains the most commonly abused drug among young people.

"We are finding that young people are experimenting with cannabis at an earlier age, the average age for young people seeking support for problematic cannabis use is around 14, though it's not unusual for 11 and 12-year-olds to now begin experimenting with cannabis.

"In the five years that Oasis has been operating there has only been one client referred in, under the age of nine."

Mike Linnell, 47, from support charity Lifeline Project, which has support staff across the country, agreed drug taking among children appeared to be on the increase in the UK. He said: "We run eight different young persons' services in the country and two years ago we didn't run any.

"Around 70% of the young people who we treat come to us through the criminal justice service. They have mostly been in trouble with the law already and drug addiction is only one of a whole series of problems they have to face. Many have suffered family problems, alcohol addiction and they are frequently in care. We have treated two or three eight-year-olds in the last couple of years and one six-year-old. It is very rare for someone that young to come to the centre."

He added: "Ten years ago they would have been sniffing solvents, which can have far more harmful effects."