Milanovic said that before the adoption of constitutional amendments this spring, it was the SDP that proposed relaxing conditions for calling a referendum, including lowering the number of signatures required for it and prolonging the time period for their collection, but the HDZ was categorically against it, only to agree with trade unions yesterday more relaxed terms when discussing the issue of labour legislation.

I congratulate the unions for having pressurised the government, he said.

All of this speaks more of the HDZ, Prime Minister Jadranka Kosor and her cabinet than of the trade unions, the chief of the strongest opposition party said, refuting speculations that yesterday's agreement would cause the SDP and unions to drift apart.

Milanovic said that it was not good that a referendum on Croatia's EU entry would be held a month or two months before parliamentary elections as the referendum would be too much burdened by electoral rhetoric and psychosis.

The government and trade union federations agreed on Tuesday evening that a referendum on which the trade unions had been insisting for some time would be held on the same day as a referendum on Croatia's accession to the European Union.

The referendum question, however, will not be about amendments to labour legislation, but will read: "Do you agree that a referendum must be called if so requested by 200,000 registered voters and that the time for the collection of the required number of voters' signatures should be 30 days?"

The current provisions stipulate that 10 percent of the electorate, or approximately 450,000 voters, must sign a petition for a referendum within two weeks in order to call a referendum.

The referendum is to be held in mid-2011, after Croatia completes accession negotiations with the European Union, PM Kosor said last night.