Over 57 percent of Swiss voters on Sunday approved a blanket ban on the construction of Muslim minarets, according to official results posted by Swiss news agency ATS.
A final tally of 26 cantons indicates that 57.5 percent of the population has voted in favor of the ban on minarets, the turrets or towers attached on mosques from where Muslims are called to prayer.
Prior to the referendum, opinion polls indicated that more Swiss would oppose rather than support the ban.
Earliest results after polls closed at mid-day (1100 GMT) showed that at least four cantons, all in German-speaking Switzerland, want a ban on minarets.
Partial results also showed that Lucerne is for the ban, while French-speaking cantons Geneva and Vaud are against.
The Swiss People's Party (SVP), Switzerland's biggest party, had forced a referendum under Swiss regulations on the issue after collecting 100,000 signatures within 18 months from eligible voters.
It claims that minarets, the turrets or towers attached to mosques from where Muslims are called to prayer, symbolize a "political-religious claim to power."
The Swiss government has asked voters to reject the call, arguing that accepting a ban would bring about "incomprehension overseas and harm Switzerland's image."
Switzerland, a nation of 7.5 million people, has an uneasy relationship with its Muslim minority of around 400,000. Islam is its second largest religion after Christianity.
Four minarets have so far been built in Switzerland and the construction of a fifth is planned.
In the run-up to the referendum, a mosque in Geneva was vandalized for the third time during the anti-minaret campaign, local media reported Saturday.
Urged to vote against proposal
Determined to stop the SVP from gaining sympathizers, Bern issued several statements calling on the Swiss to vote against the proposal.
Swiss President Hans-Rudolf Merz made a video broadcast to the nation, saying: "Muslims should be able to practice their religion and have access to minarets in Switzerland too. But the call of the muezzin will not sound here."
However, an opinion poll published a day after Merz's broadcast found that support for a ban had increased three percentage points from a month ago to 37 percent, while those who opposed the ban remained unchanged at 53 percent.
In a bid to push their case, the SVP, which had been accused of xenophobia with their election poster campaign in 2007, has once again turned to controversial tactics.
Its latest poster campaign depicts a burka-clad woman against a background of a Swiss flag upon which several minarets resembling missiles are erected, sparking an uproar in some quarters.
Switzerland's Commission Against Racism said the campaign defamed the Muslim minority, stirred up hatred and could threaten public peace.
Religious groups, including Christians, Jews and Muslims, have also come out in a rare show of unity against the right-wing proposal.
On the diplomatic front, Ekmeleddin Ihsanoglu, secretary general of the Organization of the Islamic Conference, had earlier expressed quiet confidence that Switzerland would turn down the ban.