Hungary's supreme court on Wednesday allowed the opposition Socialist Party to seek signatures demanding a referendum on a year-old law forcing most retail stores to close on Sundays.

Organizers will have to gather 200,000 signatures within 120 days to force parliament into setting a date for the vote.

The Curia, as the court is now called, agreed with a complaint from a Socialist lawmaker who said a group of large men physically prevented him from being the first to submit his referendum question at the National Election Office, which only deals with one proposed referendum at a time.

Other opposition parties said they would help the Socialists gather the signatures and asked supporters to back the referendum, which if successful would be a significant political setback for the government.

Prime Minister Viktor Orban has justified the deeply unpopular ban as a family-friendly initiative allowing employees in the retail sector to spend Sundays at home.

Turnout for a valid referendum must exceed 50 percent of voters.