Switzerland will hold a referendum on November 29 on banning the construction of new minarets after a group of politicians from the right-wing Swiss People's Party (SVP) and Federal Democratic Union gathered enough signatures last year to force a vote.

The Swiss government urged voters yesterday to reject a proposed ban on new minarets, saying it would contravene religious freedom and human rights, and could provoke extremists.

"It is not a suitable means to counter religious extremism, rather it threatens to give a boost to religious fanatics," Swiss Justice Minister Eveline Widmer-Schlumpf told a news conference webcast from Berne.

The Alpine country is home to more than 300,000 Muslims - about four per cent of the population - and has hundreds of mosques, of which only a handful have minarets. Applications to build more prompted the campaign for a ban.

Some local governments have banned a poster in favour of the ban which shows the Swiss flag, a white cross on a red background, covered in missile-like minarets and a woman wearing a black chador and veil associated with strict Islam.

An opinion poll last week showed 51 per cent of Swiss opposed a ban, while 35 per cent were in favour.

Supporters of a ban say minarets have no religious justification and are symbols of Islamic power which contravene Swiss constitutional rights to religious freedom.

Thomas Wipf, head of the Swiss Council of Religions, said Swiss identity was associated with cultural and religious diversity, but said the calling of the referendum showed Islam provoked questions, uncertainty and fear among many Swiss.

"Such questions should be discussed openly but the referendum initiative is counterproductive as it hinders dialogue rather than promoting it," he told the news conference.

The right-wing SVP, which took 29 per cent of the vote in the last election to make it the country's biggest party, has been accused of racism for anti-immigration campaigns, including a poster showing white sheep kicking a black sheep off a Swiss flag.