"That's indeed a decision, not just some formal procedure. The referendum decision will be whether Croatia belongs to Europe politically, just as geographically, historically and culturally it always has," Pusic said at a press conference on the beginning of a campaign for the EU entry referendum.

"What the citizens decide will be," she said, adding that Europe would always have influence on Croatia but that if citizens voted against accession, Croatia's influence on Europe would be questionable.

Pusic said that if the majority of Croatians voted against accession, the whole European process would come to a halt.

"We will continue with reforms, but with less money," she said, adding that Croatia would lose EUR 180 million for adjustment, EUR 449 million for projects, and more than EUR 1 billion in 2014.

The minister said the referendum could be repeated in six or more likely 12 months, but warned that Brussels might then leave Croatia to join in a package with other countries in the region.

Pusic said the Foreign and European Affairs Ministry's referendum campaign was based on five elements: access to all official documents on the ministry's website, including abridged versions of all 35 negotiation chapters and a summary of the Accession Treaty; involvement of Internet portals; national TV messages from political officials, the president, the prime minister, five ministers, and MP Jadranka Kosor; distribution of brochures; and the "Hello EU" info line by calling 0800 622 622.

Apart from national broadcasters, 17 local TV stations and 80 radio stations will also be involved in the campaign.

The preparation of the referendum and the campaign will cost HRK 4.8 million (640,000 euros).

Pusic said polls showed that about 80 per cent of citizens would vote. She called on all citizens to do so, saying the job was not completed with last month's signing of the Accession Treaty.