Italy is set to decide whether to decriminalise cannabis in a referendum next year after Italian activists gathered half a million signatures, the threshold required by law to trigger a nationwide vote.

       If the public votes to decriminalise the purchase, sale and cultivation of cannabis, it could set off a domino effect across Europe.

       The petition gathered 500,000 signatures in a week, a result described as "extraordinary but not surprising" by organisers who said the "speed of mobilisation confirms the desire for change on cannabis".

       Several other EU countries have already started their own petitions following Italy's move.

       Under Italian law, recreational use in small quantities and the consumption of marijuana for medical purposes is currently permitted. However, buying, selling and mass cultivating the drug is illegal and dealers could face up to 10 years in prison if convicted.

       Is the Czech Republic on the cusp of a cannabis boom? Cannabis capitals of Europe: Where has weed been decriminalised on the continent?

       Italy, together with other EU countries such as France, is one of the countries with the most restrictive systems in Europe.

       Campaign groups argued that decriminalising cannabis would generate thousands of jobs and would increase tax revenues for the state.

       The petition's organisers said they will continue to gather signatures until the end of the month, after which they will have to submit the referendum proposal to Italy's highest court of appeal.

       If the proposal goes through, it will then have to be sent to Italy's constitutional court for review, and the Italian president will set a date for the referendum if all is approved.

       Watch the full video report in the player above.