Police in Croatia's capital clashed with nationalist protesters Saturday, on the eve of a crucial vote on the country's membership in the European Union.

About 1,000 protesters, many of them independence war veterans, gathered in Zagreb's central square, carrying banners saying “No to EU'' or “I love Croatia,'' and chanting anti-EU slogans. Using loudspeakers, activists demanded postponement of the vote, arguing that political leaders had failed to explain to citizens all that the EU entry entails.

Police arrested several protesters who tried to take down an EU flag from a pole, while others chanted “Treason! Treason!” News reports say a few people were injured during the clashes.

On Sunday, Croatian voters will say “yes” or “no” to the question: “Do you support the membership of the Republic of Croatia in the European Union?'' Between 50 and 60 percent of the voters are expected to vote yes..

Croatia has gone through an arduous six-year negotiating process with the EU before signing an accession treaty last year. It is set to join the 27-nation bloc in July 2013.

But in recent years, a growing number of Croatian citizens has grown disillusioned with the union and many believe there is nothing to be gained by joining, while they say some hard-earned independence may be lost.

Opponents of the accession singled out Foreign Minister Vesna Pusic as the main target of their criticism. Pusic has been one of Croatia's main negotiators in the entry talks and has said that postponing the referendum could have disastrous consequences for the country's economy.

Croatia is faced with serious economic problems, including unemployment at around 17 percent and a budget gap, projected at more than 6 percent of its gross domestic product.

In addition to the referendum, the accession treaty has to be ratified by all 27 member states before Croatia can enter the bloc.

Of the six former Yugoslav republics, only Slovenia is an EU member, having entered the grouping in 2004.