In a blow for same-sex marriage advocates in Croatia, early vote results from a referendum indicate that the country will ban same-sex marriage.

The organisation U ime obitelji (In the Name of the Family), gathered enough signatures to force a referendum on whether to ban equal marriage.

The question on the referendum asked: “Do you agree that marriage is matrimony between a man and a woman?”

More than 700,000 people signed the recent petition to change the constitution to define marriage as “the lifelong union of a woman and a man.”

In early results from the referendum, around two-thirds of voters said they agreed with a constitutional amendment to ban same-sex marriage.

The BBC reports that a government official said that around a quarter of votes had been voted and verified.

Zagreb, Split, and several other large urban areas had not yet returned their results.

Hundreds of gay rights supporters in Croatia staged a mass demonstration on Saturday against the referendum.

British band The xx  issued a statement last week saying they did not condone the use of their music by U ime obitelji in its campaign.

International LGBT rights group ILGA-Europe has also called on citizens in Croatia to do the right thing in voting in favour of equal marriage.

A statement from the organisation read: “It is time for Croatia to decide if it wants to build a democratic country where every person is respected and a society where happiness of all people matters, or a country which wants to anchor discrimination in its main law.

“Vote for human rights, respect and happiness for all. Say no to discriminatory constitutional amendment.

“Glasaj protiv (vote against) this Sunday!”