The posters are considered racist and insulting to Islam, yet they are on public display in the streets and main squares of Switzerland's biggest cities ahead of tomorrow's hotly disputed referendum on whether to ban the building of minarets on mosques.
They show a menacing-looking Muslim woman covered from head to foot by a black burka, alongside a phalanx of six missile-like minarets that stand upright on the red and white Swiss flag. "Stop!" is the unequivocal message in the advertisements.
Sunday's poll to decide whether the building of new minarets should be banned is much more than the single-issue campaign it claimed to be when it was launched two years ago. It has since transformed itself into a plebiscite over Islam and a crucial test of Swiss attitudes to the nation's 400,000 Muslims. "How is it possible that such an intolerant campaign can be so successful?" said Jean Ziegler, a prominent Swiss sociologist, in a recent interview. The same question has been asked by scores of leading political and social analysts across the Alpine republic in advance of this weekend's poll.
With tensions running high, the Geneva Mosque was vandalised on Thursday by unidentified individuals who threw a pot of pink paint at the entrance. It was the third incident at the mosque this month. Previously, a vehicle with a loudspeaker drove through the area imitating a muezzin's call to prayer, and vandals threw cobblestones at the building, damaging a mosaic. The mosque is now under 24-hour police guard.
The "stop the minaret" movement, led by the anti-immigrant Swiss People's Party (SVP), has prompted a national debate. A petition in support of it was signed by more than 115,000 Swiss citizens, well over the 100,000 needed to legally force a referendum.
Walter Wobmann, an SVP MP, is one of the campaign's biggest supporters and claims minarets symbolise an encroaching Islamisation of Swiss society, with its traditional way of life threatened by strict sharia law. "Among other things, Islamic law is about honour killings, forced marriages, [female] circumcision, wearing of the burka, breaking school rules and even stonings," he says.
In 2007, the SVP fought a general election using xenophobic campaign posters that depicted a white sheep kicking a black sheep out of Switzerland. The United Nations said the posters were "openly racist". The new minarets poster has been banned in some cities but seems omnipresent in others. Zurich and Geneva, for example, both said the principle of free speech meant they must be displayed.
Switzerland's Muslim community has grown from about 16,000 in the late 1960s to an estimated 400,000, or 5 per cent of the population, today. Most are Turks, Bosnians or Albanians. Their leaders are dismayed by the campaign against minarets. "It discriminates against all those Muslims who are interested in social and inter-religious dialogue," said Hisham Maizar, president of Switzerland's Islamic Federation.
Youssef Ibram, an imam at Geneva's mosque, added: "We may only be a minority but for that reason we take particular notice of how the majority treats us. If only 5 per cent vote in favour of a ban it will be a defeat for us. It will show we are not welcome in Switzerland."
Young worshippers at the mosque claim the campaign has led to them being feared by non-Muslims. However the negative publicity, coupled with the bad press Switzerland received in 2007 from the SVP's election campaign, has prompted other parties to take action.
Ueli Leuenberger, the Green Party president, has toured mosques to apologise and express solidarity with Muslims. Norbert Hochreutener, a conservative Christian Democrat MP, also opposes the campaign. He said: "The only effect a minaret ban would have would be to create a feeling among Muslims that they have been discriminated against."
Polls suggest the referendum could be close-run. With only a slim majority of those questioned expressing opposition or a tendency to oppose a ban, undecided voters could yet sway the ballot towards the "'yes" campaign. "It's fine to build minarets in a Muslim country, not in Switzerland," said Rolf Waechtler, a jobless electrical fitter.