The campaign poster was blatant in its xenophobic symbolism: Three white sheep kicking out a black sheep over a caption that read "for more security." The message was not from a fringe force in Switzerland's political scene but from its largest party.

The nationalist Swiss People's Party is proposing a deportation policy that anti-racism campaigners say evokes Nazi-era practices. Under the plan, entire families would be expelled if their children are convicted of a violent crime, drug offenses or benefits fraud.

The party is trying to collect the 100,000 signatures needed to force a referendum on the issue. If approved in a referendum, the law would be the only one of its kind in Europe.

"We believe that parents are responsible for bringing up their children. If they can't do it properly, they will have to bear the consequences," Ueli Maurer, president of the People's Party, told The Associated Press.

Ronnie Bernheim of the Swiss Foundation against Racism and Anti-Semitism said the proposal was similar to the Nazi practice of "Sippenhaft" — or kin liability — whereby relatives of criminals were held responsible for his or her crimes and punished equally.

Similar practices occurred during Stalin's purges in the early days of the Soviet Union and the 1966-76 Cultural Revolution in China, when millions were persecuted for their alleged ideological failings.

"As soon as the first 10 families and their children have been expelled from the country, then things will get better at a stroke," said Maurer, whose party controls the Justice Ministry and shares power in an unwieldy coalition that includes all major parties.

He explained that his party has long campaigned to make deportation compulsory for convicted immigrants rather than an optional and rarely applied punishment.

The party claims foreigners — who make up about 20 percent of the population — are four times more likely to commit crimes than Swiss nationals.

Bernheim said the vast majority of Switzerland's immigrants are law-abiding and warned against generalizations.

"If you don't treat a complicated issue with the necessary nuance and care, then you won't do it justice," he said.

Commentators have expressed horror over the symbolism used by the People's Party to make its point.

"This way of thinking shows an obvious blood-and-soil mentality," read one editorial in the Zurich daily Tages-Anzeiger, calling for a broader public reaction against the campaign.

So far, however, there has been little popular backlash against the posters.

"We haven't had any complaints," said Maurer.

The city of Geneva — home to Switzerland's humanitarian traditions as well as the European headquarters of the United Nations and the U.N. Refugee Agency, or UNHCR — said the campaign was likely to stir up intolerance.

The UNHCR said the law would run contrary to the U.N. refugee convention, of which Switzerland is a signatory.

But observers say the People's Party's hardline stance on immigration could help it in the Oct. 21 national elections. In 2004, the party successfully campaigned for tighter immigration laws using the image of black hands reaching into a pot filled with Swiss passports.

"It's certainly no coincidence that the People's Party launched this initiative before the elections," said Oliver Geden, a political scientist at the Berlin Institute for International and Security Affairs.

He said provocative campaigns such as this had worked well for the party in the past.

"The symbol of the black sheep was clearly intended to have a double meaning. On the one hand there's the familiar idea of the black sheep, but a lot of voters are also going to associate it with the notion of dark-skinned drug dealers," said Geden.

The party also has put forward a proposal to ban the building of minaret towers alongside mosques. And one of its leading figures, Justice Minister Christoph Blocher, said he wants to soften anti-racism laws because they prevent freedom of speech.