Wellington, Aug 31 NZPA - The Ministry of Health has issued new guidelines on how to clean up P labs.

The guidelines outline everything from how to establish if there is a risk and which government agency needs to get involved.

Health Minister Tony Ryall said the guidelines for cleaning up clandestine laboratories used to manufacture methamphetamine, or P, were needed.

"The guidelines are a first for this country and were requested by the councils, landlords and communities who have to clean up these sites," he said.

"Most illegal meth labs are set up in residential properties where they can leave extremely hazardous chemical residues for the offenders and their families living there, or for the people cleaning up after them."

The number of labs police discovered rose from nine in 2000 to 135 in 2009.

The guidelines provided nationally consistent and practical advice for checking for and dealing with contaminated sites so they can be reoccupied without serious risk to health.