Planning applications for new minarets are almost always refused
The people of Switzerland have been voting on whether to ban the building of minarets in their country.
The proposal is backed by the Swiss People's Party (SVP), the largest party in parliament, which claims minarets are a sign of Islamisation.
Opponents say a ban would discriminate, and that the campaign has stirred hatred. The government opposes a ban.
Switzerland is home to some 400,000 Muslims and has just four minarets. Referendum results are due at 1700GMT.
Islam is the most widespread religion after Christianity, but it remains relatively hidden.
There are unofficial Muslim prayer rooms, and planning applications for new minarets are almost always refused.
Supporters of a ban claim that allowing minarets would represent the growth of an ideology and a legal system - Sharia law - which are incompatible with Swiss democracy.
But others say the referendum campaign has incited hatred. On Thursday the Geneva mosque was vandalised for the third time during the campaign, according to local media.
Opinion polls ahead of the vote are close, with signs that a small majority will reject the ban.
The BBC's Imogen Foulkes reports from Bern that that would be a relief to the Swiss government, which fears banning minarets would cause unrest among the Muslim community and damage Switzerland's relations with Islamic countries.
Swiss President Hans-Rudolf Merz said: "Muslims should be able to practice their religion and have access to minarets in Switzerland too. But the call of the muezzin [call to prayer] will not sound here."
Amnesty International has warned that the ban would violate Switzerland's obligations to freedom of religious expression.
Elham Manea, founder of the Forum for a Progressive Islam, pointed to the recent construction of Sikh temples and Serbian Orthodox churches, saying a ban on minarets alone would be discriminatory.
"If you are telling me that we are going to ban all religious symbols from all religious buildings, I would not have a problem with that," she said.
"But if you are just telling me that we are going to target only the Muslims, not the Christians, not the Jews, not the Sikhs, only the Muslims, then I have a problem with it because it is discrimination."
Most of Switzerland's Muslims come from former Yugoslavia. There is no history of Islamic extremism, but supporters of a ban say minarets are far more than religious architecture.
They claim allowing them would be a sign that Islamic law is accepted in Switzerland.
Sunday's referendum is being held after the SVP collected 100,000 signatures from eligible voters within 18 months calling for a vote.
SVP member of parliament Ulrich Schluer said the referendum campaign had helped integration by encouraging debate. He rejected the charge of discrimination.
"Every Muslim is allowed to come together with other Muslims to have the religion together," he told the BBC.
"But a minaret is a political symbol. It is a symbol for introducing, step-by-step, Sharia rights also in Switzerland, parallel to the Swiss law which is a result of Swiss democracy. And this is the problem. It is nothing against Muslims."
In recent years many countries in Europe have been debating their relationship with Islam, and how best to integrate their Muslim populations.
France focused on the headscarf, while in Germany there was controversy over plans to build one of Europe's largest mosques in Cologne.