Far right groups in Switzerland have collected enough signatures to force a nationwide referendum on banning minarets, the distinctive towers of Islamic architecture.

In what is being seen as a sign of growing Islamophobia in Europe, more than 100,000 Swiss citizens signed a petition to halt the construction of minarets.

Under Switzerland's direct democracy rules, that level of support is enough to trigger a referendum. The Swiss interior ministry today confirmed a vote would take place, without setting a date.

The petition was launched by Ulrich Schlüer an MP from the controversial Swiss People's party, which was accused of racist campaigning last year.

In a bid to get immigrants' families deported if their children had been convicted of violent crime, the party ran an advertising campaign showing three white sheep on a Swiss flag kicking out a black sheep with the caption: "For more security."

The president of Switzerland, Pascal Couchepin, said the government would recommend that voters rejected the proposed minaret ban.

The organisers of the petition argue that the minarets, which are used on mosques, are a symbol of political and religious claims to power, not just a religious sign.

Schlüer said last year: "We've got nothing against prayer rooms or mosques for the Muslims. But a minaret is different. It's got nothing to do with religion; it's a symbol of political power."

If Schlüer's camp wins the referendum, the Swiss parliament must pass a law enshrining a minaret construction ban in the constitution.

Opponents say such a ban would violate religious freedom.

More than 310,000 of Switzerland's 7.5 million population are Muslims, according to the federal statistical office.

The UN expert on racism, Doudou Diene, has said the campaign is evidence of an "ever-increasing trend" toward anti-Islamic actions in Europe.