ZAGREB, Croatia — A majority of Croatians have voted in a referendum to ban gay marriages in what is a major victory for conservatives in the newest European Union nation.

The state electoral commission, citing initial results, said 65 percent of those who voted Sunday answered "yes" to the referendum question: "Do you agree that marriage is matrimony between a man and a woman?" About 34 percent voted against.

The result meant that Croatia's constitution will be amended to ban same-sex marriage.

The vote has divided Croatia. Liberal groups have said the referendum's question infringes on basic human rights.

The Catholic Church-backed groups have gathered 750,000 signatures in its support.