(ANSA) - LUBIANA, MAR 21 - The conservative Slovenian Democratic Party (Sds) - the main opposition force led by former Prime Minister Janez Janša - collected the necessary signatures to hold a referendum to repeal the Artistic Merit Pension Supplement Act, which was passed last January. Political controversy erupted over this issue, with the majority talking of a populist move and campaigning to the detriment of taxpayers. According to referendum legislation, the vote should take place no sooner than 30 days after the referendum is called, which is when the signatures will be deposited in Parliament, as early as next week. The vote is expected to be highly polarized and does not require a quorum. (ANSA).