ROME (Reuters) - Italy's Constitutional Court on Wednesday rejected a request to hold a referendum on legalising the cultivation of cannabis, provoking the ire of promoters who called the decision a blow to democracy.

       The referendum proposal sought to legalise the growing of weed for personal use and ease sanctions on other cannabis-related crimes, with offenders no longer risking prison sentences for selling small amounts of the drug.

       Giuliano Amato, the Constitutional Court president, said the referendum included other narcotics considered to be hard drugs, which could not be liberalised.

       "This is enough to make us violate multiple international obligations," Amato, a former prime minister, told a news conference.

       Lawmaker Riccardo Magi, one of the referendum's leading advocates, told Reuters the court's decision was "a terrible blow to democracy," after hundreds of thousands of people had signed up to the proposal.

       "It's almost impossible to hold a referendum in Italy," he said.

       On Tuesday, the Court turned down a right-to-die referendum, saying the proposal did not safeguard minimum constitutional standards governing the protection of human life.

       The campaigns launched on the right-to-die and cannabis referendums had gathered together over 1.8 million signatures.

       However five other, less high profile referendum proposals about largely arcane aspects of the justice system were accepted. These will be submitted to the popular vote next spring.

       (Reporting by Angelo Amante, editing by Gavin Jones, William Maclean)