Mr Simich, in reply to a question on Tuesday by Te Tai Hauauru MP Tuku Morgan, said he firmly believed that people who used marijuana were unwise and were likely to damage themselves.

The former undercover agent, whose name has been suppressed by the High Court, said Mr Simich was being hypocritical if he did not act to stop use of the drug among undercover police as part of their training and in the field.

Police policy is for undercover agents to simulate smoking in the field unless smoking is unavoidable.

A spokesman said yesterday that Mr Simich would not enlarge on what was his personal opinion, and could not comment on police operational matters.

The former agent claimed officers were required to smoke marijuana every day during their training to go undercover to familiarise themselves with its affects and to build up tolerance.

Agents did not simulate smoking marijuana in the field because it was "the signature of an undercover agent and they know that if they are caught it is a death sentence".

He said some agents were making evidential statements when they were under the influence of marijuana and mistakes were being made. Agents were then forced to lie in court to cover up.

The former agent, who is a spokesman for a group of more than 50 former policemen who are claiming exemplary damages from the police for stress and addiction, said a recent survey showed a 20 to 50 per cent rate of drug addiction among undercover agents.

Police national headquarters CIB manager Detective Superintendent Bill Bishop said there were no plans to change the training of undercover agents.

He said smoking was not taught, but "risk minimisation" was. This was supported by psychological and medical counselling before, during and after deployment.