The home secretary, Charles Clarke, today ruled out another reclassification of cannabis despite recent warnings that the drug can cause serious mental illness.
Mr Clarke said cannabis would not be changed back to a class B drug, instead announcing a public health campaign to warn people of the health risks associated with its use.
He told MPs that his decision to keep cannabis as a class C drug had followed advice from the Advisory Council on the Misuse of Drugs, and was supported by police and most drug and mental health charities.
The council's unpublished report is said to have concluded that the risk of someone developing schizophrenia as a result of using cannabis was "very small".
It is believed to have said it was a "substantially less" harmful drug than those currently classified as class B, including amphetamines such as speed and barbiturates.