VATICAN CITY - Pope Benedict XVI heads to the Balkans this weekend with a pro-European Union message for a region being forced to account for its bloody past to join the EU bloc.

Benedict was to leave today for an overnight trip to Croatia, a Catholic bastion visited three times by his predecessor. The long-planned trip has taken on fresh relevance following the arrest in neighboring Serbia of fugitive wartime Gen. Ratko Mladic on war-crimes charges.

Like Serbia, which extradited Mladic to the Hague tribunal as a precondition for starting EU membership talks, Croatia had to produce its top wartime fugitive, Gen. Ante Gotovina, to fulfill key EU accession requirements.

Benedict has long supported Croatia's EU bid, eager to have another stalwart Catholic country - 89 percent - in the bloc alongside Italy and Poland. But some Croatians have become soured on the EU following their drawn-out accession process and Gotovina's conviction on war crimes.

The Hague tribunal in April sentenced Gotovina to 24 years in prison for his role in a 1995 military offensive intended to drive Serb rebels out of land they had occupied for years along Croatia's southern border with Bosnia.

After his conviction, thousands of Croatian war veterans massed in Zagreb and ripped EU flags and denounced Croatia's pro-Western government, which has made EU membership its mantra.

Gotovina is revered among many Croats for his role in the battle that sealed Croatia's independence from Serb-led Yugoslavia after four years of conflict.

Support for EU membership now officially hovers around 50 percent.

Nino Djula, editor of the liberal-leaning newsweekly Globus, said the anger at the sentence wasn't because Croatians necessarily thought Gotovina would be acquitted, but because they had not expected such a long sentence.

"The feeling of injustice is constant, but the anger was temporary," he said. "I don't think this anger will lead to any serious euroskepticism."

Croatia is likely to be the next nation to join the union, possibly in 2013, with a decision possible this month or next to formally close accession negotiations. Kosor's conservative government is banking on a completion of negotiations before elections expected later this year or early 2012.

Benedict has been keen to see Croatia, which is 89.8 percent Catholic, join the EU and the visit to Zagreb has been seen as a major boost for the government's bid. The Vatican was one of the first countries to recognize Croatia's independence in 1991.

In April, Benedict told Croatia's new ambassador to the Holy See that the country shouldn't worry about losing its identity by joining the EU, a message possibly intended for die-hard nationalists who have long been skeptical of entering the EU.

"You needn't fear making a determined claim for respect of your own history and religious and cultural identity," Benedict said. On the contrary, he said, Europe needs to be reminded of its Christian heritage. "Affirming that Europe doesn't have Christian roots is like pretending that a man can live without oxygen or food."

Vatican spokesman the Rev. Federico Lombardi cited Benedict's remarks when asked about the anti-EU sentiment that had erupted following the Gotovina verdict.

While Benedict is unlikely to refer directly to the Gotovina case, Lombardi said, "I imagine there will be references to this bigger theme of the culture, tradition and identity of the Croatian people and their hopes of entering the EU."

Like many countries Benedict has visited recently amid the global economic downturn, there is some discontent in Croatia about the estimated $2.9 million cost of the visit. A protest was planned for today, unusual for this country which welcomed Pope John Paul II without opposition during his three visits.