Smoking potent cannabis was linked to 24% of new psychosis cases analysed in a study by King's College London.
The research suggests the risk of psychosis is three times higher for users of potent "skunk-like" cannabis users than non-users.
The study of 780 people was carried out by KCL's Institute of Psychiatry, Psychology and Neuroscience.
A Home Office spokesman said the report underlines the reasons why cannabis is illegal.
Scientists found the risk of psychosis was five times higher for those who use it every day compared with non-users.
They also concluded the use of hash, a milder form of the drug, was not associated with increased risk of psychosis.
Psychosis refers to delusions or hallucinations that can be present in certain psychiatric conditions such as schizophrenia and bipolar disorder.
"Compared with those who had never tried cannabis, users of high potency 'skunk-like' cannabis had a threefold increase in risk of psychosis,' said Dr Marta Di Forti, lead author on the research.
She added: "The results show that psychosis risk in cannabis users depends on both the frequency of use and cannabis potency."
A Home Office spokesman said the findings backed up the government's approach: "Drugs such as cannabis are illegal because scientific and medical evidence demonstrates they are harmful.
"This report serves to emphasise how they can destroy lives and communities."
The spokesman added "there are positive signs our drugs strategy is working", claiming "people going into treatment today are more likely to recover now than in 2010".
Skunk contains more THC than other types of cannabis, which is the main psychoactive ingredient.
Unlike skunk, hashish - cannabis resin - contains substantial quantities of another chemical called cannabidiol or CBD and research suggests this can act as an antidote to the THC, counteracting psychotic side effects.
I may have mentioned this before ;-)
I may have mentioned this before ;-)
“If you trust in yourself, and believe in your dreams, and follow your star. . . you'll still get beaten by people who spent their time working hard and learning things and weren't so lazy.”