The Italian Senate on Thursday approved a controversial electoral reform law that introduces a mixed and proportional system that will require parties to win huge majorities to be able to govern.

The law's approval, which its supporters said was necessary as Italy currently lacks a valid electoral system and elections are next to be held in 2018, was met with strong protests from the Five Star Movement (M5S) and a large part of the left.

The new electoral system, known as "Rosatellum Bis," was approved in a secret vote with 241 senators casting their ballots in favor, 61 against and one abstaining and must now be signed by President Sergio Mattarella.

Under Rosatellum Bis, 36 percent of seats in the Chamber of Deputies _ the lower house of parliament _ and in the Senate would be elected with a first-past-the-post method, while the rest would be selected based on proportional representation.

The system means that parties would have to form coalitions in order to rule, but the M5S, who have always insisted they would hold power alone, claimed the reform had been drawn up by the other parties in an effort to keep them from power.