The union-led referendum initiative "67 is too much" announced in Zagreb's main square at midnight on Saturday that they had gathered over 600,000 signatures for a referendum to prevent the statutory retirement age from being raised from 65 to 67.

According to the law, organisers of a referendum are required to gather the signatures of at least 373,568 voters, or 10 percent of the electorate, before formally filing a referendum petition.

The initiative’s national coordinator Mirela Bojic told a press conference that the signatures would be submitted to parliament within two weeks, after the signature sheets were thoroughly checked.

The leader of the Federation of Autonomous Trade Unions of Croatia (SSSH), Mladen Novosel, said they expected the referendum to be held in early September.