Croatians are to cast ballots on Sunday in a referendum that could ban same-sex marriage in this conservative and Catholic country, an issue that polarises the European Union's newest member.

Discrimination or protection of family values, human rights or gay activists' self-interest, secular state or theocracy -- passions ran high in Croatia during the past few weeks as opponents and supporters of the vote led heated debates over gay marriage.

The referendum on whether to amend the country's constitution to define marriage as a "union between a woman and a man" is the result of a Church-backed initiative. Croatia's constitution currently does not define marriage.

The centre-left government's announcement of a bill enabling gay couples to register as "life partners" sparked fears of many conservatives in Croatia, which only joined the European Union in July, that same-sex marriage would be allowed.

In May, the Church-backed In the Name of the Family group collected almost 700,000 signatures seeking a nationwide vote on marriage definition.

"We believe that marriage, children and family are so important issues that the whole society has to decide on them," the leader of the initiative, Zeljka Markic, told AFP.

But, the vote has split the country's population of 4.2 million.

The government, human rights activists and prominent public figures have all spoken out against the referendum, urging people to cast a 'no' vote.

"It would not be good that Croatia appears to be a country of intolerance," President Ivo Josipovic told journalists.

On Saturday more than 1,000 people braved the cold and rainy weather to take part in a protest march through central Zagreb arguing the vote was discriminatory.

Carrying banners reading "Against fascism" or "Homosexuality is not a choice but hatred is" they also warned that the referendum might lead to other conservative initiatives targeting minorities or sensitive issues such as abortion.

"How would you feel if you would have to ask four million people for a permission to get married?" Ljubomir Mateljan said bitterly.

"This is exactly how I and my fiance feel now," the 31-year-old gay rights activist from Split, on the central Adriatic coast, told AFP.

But in a country where almost 90 percent of the population are Roman Catholics, the still powerful Church has called on followers to vote 'yes'.

"Marriage is the only union enabling procreation," said Croatia's Cardinal Josip Bozanic in a letter read out in churches.

"This is the key difference between a marriage... and other unions."

The latest survey showed that 68 percent of Croatians plan to vote 'yes' on Sunday compared to 27 percent against.

"Marriage is a union of a man and a woman, the only union that can bring children in a natural way and it should be in the state's interest to protect it," Mario Lipovac, a conservative activist, told AFP.

Attitudes towards gay rights have slowly become more liberal since Croatia's first Gay Pride parade was held in Zagreb in 2002, when dozens of participants were beaten up by extremists.

Gay rights marches are now staged regularly if still under strong security, while gay rights are more openly discussed in the media and homosexuals are becoming less fearful of "coming out".

In 2003 Croatia adopted a law recognising same-sex couples who have lived together for at least three years. Yet apart from the official acknowledgement, the measure has granted them few rights.

Sunday's vote is the first citizens-initiated referendum since Croatia's independence from the former Yugoslavia in 1991.

Under Croatian law, a referendum does not require a majority voter turnout to be valid.

Polling stations will open at 0600 GMT and close 12 hours later while first partial results are expected late on Sunday.

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  • Netherlands

    The Netherlands was the first country to recognize gay marriage in <a href="" target="_hplink">2001</a>. <em>Pictured: Jan van Breda and Thijs Timmermans.</em>

  • Belgium

    Belgium legalized same-sex marriages in <a href="" target="_hplink">2003. </a> <em>Pictured: Marion Huibrecht and Christel Verswyvelen.</em>

  • Spain

    Spain legalized gay marriage in <a href="" target="_hplink">2005</a>.

  • Canada

    Canada followed Spain and approved gay marriage in <a href="" target="_hplink">2005. </a>

  • South Africa

    South Africa legalized same sex marriage in <a href="" target="_hplink">2006.</a> <em>Pictured: Vernon Gibbs and Tony Hall. </em>

  • Norway

    Norway followed suit in <a href="" target="_hplink">2009.</a> <em>Norwegian finance minister and chairwoman of the Socialist Left party Kristin Halvorsen (L) stands next to wedding figurines outside the House of Parliament in Oslo on June 11, 2008, where she celebrated the passing of a new law awarding equal rights to same sex partnerships as those enjoyed by heterosexual marriages. (Getty)</em>

  • Sweden

    Sweden recognized same sex marriage in <a href="" target="_hplink">2009.</a> <em>Pictured: Johan Lundqvist (L) and Alf Karlsson. </em>

  • Portugal

    Portugal recognized gay marriage in <a href="" target="_hplink">2010.</a> <em>Pictured: Teresa Pires and Helena Paixao. </em>

  • Iceland

    Iceland legalized gay marriage in <a href="" target="_hplink">2010.</a>

  • Argentina

    Argentina legalized same sex-marriage in <a href="" target="_hplink">2010.</a> It was the only Latin American country to do so. <em>Pictured: Giorgio Nocentino (L) and Jaime Zapata.</em>

  • New Zealand

    New Zealand<a href="" target="_blank"> became the first</a> Asia-Pacific nation (and the 13th in the world) to legalize same-sex marriage. <em>Pictured: Jills Angus Burney (L) and Deborah Hambly.</em>

  • Denmark

    Denmark became the first country to allow the registration of gay partnerships in 1989. In 2012, Denmark's <a href="" target="_blank">Parliament approved </a>a law allowing same-sex couples to get married in formal church weddings instead of the short blessing ceremonies that the state's Lutheran Church offered.

  • Uruguay

    The Uruguay Parliament lawmakers passed the <a href="" target="_blank">"marriage equality project"</a> in Montevideo, Uruguay,Wednesday, April 10, 2013.

  • U.S.A.

    Same-sex marriage is legal in 13 U.S. states and Washington DC.

  • Brazil

    Some <a href="" target="_blank">parts of Brazil</a> allow same-sex marriage (AL, BA, CE, DF, ES, MS, PR, PI, SE, and SP).

  • Mexico

    Some areas of Mexico allow gay marriage, such <a href="" target="_blank">as Mexico City</a>.

  • France

    France legalized same sex marriage in <a href="" target="_hplink">2013</a>. Pictures: an illustration made with plastic figurines of men is seen in front of the Palais Bourbon, the seat of the French National Assembly. (JOEL SAGET/Getty Images)

  • Britain

    Britain legalized gay marriage on July 17, 2013 after Queen Elizabeth II gave her royal stamp of approval. Gay marriages are set to begin in England and Wales in the summer of 2014.