The latest change in policy is a reversal of a previous move to reclassify the drug from Class B to Class C.

"While cannabis has always been illegal, reclassifying it to a Class B drug reinforces our message to everyone that it is harmful and should not be taken," said Jacqui Smith, Home Secretary.

Whilst the Home Secretary acknowledged that cannabis use fell after reclassification, she affirmed her position that a tougher approach was needed.

"Fewer people are taking cannabis, but it is crucial that this trend continues," she said.

"I am extremely concerned about the use of stronger strains of cannabis, such as skunk, and the harm they can cause to mental health."

"This is the next step towards toughening up our enforcement response -- to ensure that repeat offenders know that we are serious about tackling the danger that the drug poses to individuals and, in turn, communities."

Users caught twice will face an £80 fine on each occasion -- a third infraction will lead to prosecution in a court of law and a possible jail term.

The maximum penalty for possession will be go up from two years in jail to five years, or an unlimited fine.

Those convicted of supplying the drug could serve up to 14 years in prison.

But the move is in direct opposition to advice given to the government by the Advisory Council on the Misuse of Drugs, the body charged with offering expert advice to the Home Office.

The Home Office has instead followed the line taken by the Association of Chief Police Officers (ACPO) who favour a tougher approach to law enforcement on cannabis.

It is believed that some police officers were opposed to the downgrading of cannabis as minor convictions for possession often led them to receive intelligence that they may not have done otherwise.

"There is evidence of increasing harms to community safety associated with criminal behaviour around the cultivation, distribution and the use of cannabis," said Tim Hollis, Chief Constable of Humberside Police and ACPO's lead on drugs.

"While enforcement alone will not provide the total solution to a crime that is a global problem, this will act as a deterrent, along with better education about the impact of drugs."