Pusic said parliamentary elections must be held before a referendum on Croatia's accession to the European Union, otherwise "we risk losing the referendum." "One should not gamble with that. We need elections and then the referendum."

Zoran Milanovic of the Social Democratic Party (SDP) said the opposition would not accept Kosor's invitation to come to the government until she came to parliament to discuss political and social issues and the EU entry talks.

He said the opposition went to the government to discuss those issues a number of times, "but enough is enough," adding the opposition would not go to the government before Kosor came to parliament and explained accusations that the opposition was responsible for inciting riots at recent demonstrations in Zagreb.

Milanovic said the completion of the EU entry talks should also be discussed in parliament, specifically which benchmarks Croatia had to meet to close the negotiation chapter regulating the judiciary and fundamental rights and what the opposition could do.

He added the benchmarks, defined by the European Commission, were very arbitrary. "They are written in such a way that they can and don't have to be met, in such a way that nobody can meet them if the evaluator is not in a good mood. That's a fact and we need to talk about it in parliament."

Milanovic said the opposition would do its best to have the chapter closed, so that the PM could say when parliamentary elections would be held.

"We insist on that, otherwise we are endangering the outcome of the referendum on Croatia's EU accession, which we believe must succeed," he said.

"If the negotiations are completed in June and we wait for more than half a year until the referendum, that won't be good and you know it. Tell this to yourself and to your party president and the prime minister," Milanovic told MPs of the Croatian Democratic Union (HDZ).

Damir Kajin of the Istrian Democratic Party (IDS) said the most realistic election date was "24 hours after the completion of the negotiations with the EU, and if they are not completed, then five minutes after that."

Kajin said the HDZ's attitude of disregard had made 70 per cent of the citizens support the ongoing protests, adding "people are furious but won't equate the opposition and those in power."

Dinko Buric of the HDSSB said Kosor was out of her depth. "The statements the PM and her ministers are making lately are a sign of total disorientation and 612 days after Kosor came to power, people have taken to the streets and the government is in the clouds."

Speaking on behalf of the HDZ group, Deputy Speaker Vladimir Seks said the government-parliament relationship was regulated by the constitution, meaning that the opposition's requests should be dealt with in accordance with the constitution and not by ultimatums that elections be held immediately.

"If you want the government to get a vote of no-confidence, do it in line with parliamentary procedure," Seks said, adding that a parliamentary decision was necessary to invite Kosor to parliament, not just a request by the opposition.

Speaker Luka Bebic said he would convey the opposition's request to Kosor.