By Imogen Foulkes BBC News, Geneva

A political row has broken out in Switzerland over a campaign poster from the right-wing Swiss People's Party, aimed at deporting foreigners - residents without Swiss citizenship - who commit crimes.

The poster, which shows three white sheep kicking a black sheep against a backdrop of the Swiss flag, can be seen all over the country ahead of general elections at the end of October.

The controversial poster bears the slogan "For more security"

Immigrant groups in Switzerland, left-wing parties and the United Nations complain that the poster is blatantly racist.

The Swiss People's Party, currently the largest in parliament and leading in the opinion polls, is pushing for a new law which would authorise the expulsion of foreign families, should any family member be found guilty of violent crime, drugs offences or benefit fraud.

Over 20% of Switzerland's population is foreign. Most have been in the country for many years, and around a third of them were born in Switzerland.

Swiss citizenship remains very difficult to come by, and being born in the country does not give the children or even grandchildren of immigrants the right to be Swiss.

Crime figures

The Swiss People's Party claims that foreigners commit more crimes than the Swiss, and says this justifies deporting them and their families.

We've had an unbelievably positive response. It shows just how necessary our campaign is Matthias Mueller Swiss People's Party spokesman

In fact, crime statistics are not at all clear, partly because not all Swiss regions count crime in the same way.

A recent study by the Federal Department for Foreigners found that while, at first glance, foreigners appear to be committing more crime than the Swiss, foreigners, especially young men, are also more likely to be charged - whereas young Swiss may be let off with a caution for the same offence.

The study also found that young foreigners living in Switzerland were more likely to be unemployed and living in socially deprived backgrounds, than the Swiss.

But despite the complex nature of the problem, the blunt approach has clearly struck a chord with many voters.

Matthias Mueller, spokesman for the party, says the campaign has attracted huge support.

"We've had an unbelievably positive response," he said. "It shows just how necessary our campaign is."

Storm of criticism

But now that the poster is visible all over Switzerland, there has been a storm of criticism too.

Right-wing parties fear Swiss traditions are under attack

Swiss Jewish groups say the symbolism of the poster, and its use of colour, is frighteningly reminiscent of Nazi propaganda.

"I think it's a disgusting way to conduct politics," said Alfred Donath, president of the Swiss Federation of Jewish Communities.

"It is entirely contrary to Switzerland's humanitarian tradition, and really not the way we should do things."

Meanwhile the United Nations special rapporteur on racial discrimination, Doudou Diene from Senegal, has asked the Swiss government for an official explanation of the campaign.

The Swiss People's Party, which wants to pull Switzerland out of the UN Convention against Racism, and abolish the country's own Federal Commission on Racism, is dismissive of UN opinion.

"The UN should not be meddling in internal Swiss politics," said Matthias Mueller. "We have got freedom of speech in our country. Obviously [Mr Diene] has not understood our culture of democracy. I would suggest he reads up on it."

Video withdrawn

The Swiss People's Party is used to criticism of its tactics, but this time there are signs it may have gone too far.

Another poster, showing veiled Muslim women accompanied by the question, "Where are we living, Baden or Baghdad?", is now the subject of an investigation to determine whether it violates Switzerland's anti-racism laws.

Meanwhile, a campaign video showing what it is claimed are young hooded foreigners committing violent crimes was withdrawn after the Swiss youngsters who actually took part complained they had been told they were taking part in a crime-prevention video.