Italy's supreme court has ruled that cultivating cannabis on a small scale for personal use is legal, in a landmark judgment expected to provoke controversy.

After being asked to clarify previous conflicting interpretations of the law, the Court of Cassation decided that the crime of growing narcotic drugs should exclude "small amounts grown domestically for the exclusive use of the grower".

Details of the decision, made on December 19th but revealed in recent days, have already provoked a critical response from organisations that deal with drug-dependency, suggesting the debate on this ruling could run.

"The court has opened the way, now it's up to us," said Matteo Mantero, a senator from the governing coalition party, the 5-Star Movement. Mr Mantero presented an amendment to the 2020 budget calling for legalisation and regulation of domestic cannabis use, but it was ruled inadmissible by the senate speaker from Silvio Berlusconi's conservative Forza Italia party.

"Drugs cause harm, forget about growing them or buying them in shops," Matteo Salvini, leader of the right-wing League Party said in a statement on Friday, in reference to shops selling low-strength "legal weed" that are widespread in Italy.

Maurizio Gasparri, a senator from Forza Italia which is allied to the League, said the first law the centre-Right coalition would approve if it came to power "will cancel the absurd verdict of the court".