Their critics call them “Birkenstock racists” and accuse them of marrying Green ideology with the toxic xenophobia of the far right. But if the controversial “Ecopop” movement wins a key referendum in Switzerland today there are fears that they could ring some alarming changes in the Alpine nation.

Ecopop takes its name from the French terms “Ecologie” and “Population”. The movement believes that there are too many people in the world and that draconian immigration cuts and massive investment in birth control for the developing world are the only ways to address the problem.

Ecopop wants Switzerland to slash its annual immigration to 0.2 percent of the country’s population. “We don’t want to see our countryside covered in concrete because it has to cope with an immigrant population flood,” said Andreas Thommen one of Ecopop’s activists, a farmer and father of three. “I don’t’ mind foreigners, but it the numbers that count,” he says.

If Ecopop’s policy were enforced it would mean cutting Switzerland’s annual immigration from the current 80,000 to just 16,000. Critics point out that such a move would torpedo the country’s key agreements with the European Union on free movement of labour and spell disaster for the economy.

But the movement’s also has another aim: it wants to oblige Switzerland to spend at least ten percent of its annual development aid budget on voluntary birth control and family planning projects in the Third World. Ecopop claims its objective, which is based on a 1972 Club of Rome study entitled “The limits of growth”, is to prevent a global population explosion.

Swiss voters will today take part in a nation wide referendum which could result in Ecopop’s highly controversial policies becoming law. “Stop Overpopulation” is the movement’s simple campaign slogan. Opinion poll predictions have varied. Some have suggested that Ecopop could win with a slim 53 percent majority. Others forecast that it will obtain only 39 percent of the vote.

But recent Swiss voting habits on immigration have done little to calm the fears of Ecopop’s detractors. In February Switzerland’s Green and Social Democratic parties were shocked by the results of a referendum backed by the country’s right-wing populist Swiss People’s Party (SVP) which came out strongly in favour of major immigration restrictions.

In February most of the votes in favour of immigration control came from rural Swiss regions which are less exposed to foreigners than the cities, but where xenophobia nevertheless remains high: “We never believed, it would happen and we are still having difficulty in introducing the controls,” said Andreas Gross a leading Social Democrat.

Swiss businessmen are alarmed by the consequences of an Ecopop win because of the country’s huge dependence on foreign labour. “The Swiss would not just be cutting into the branch they are sitting on, they would be sawing it off, warned “Severin Schwan, the head of the Basel pharmaceutical concern Roche.

Ecopop has managed to attract followers who, at face value, would seem to be at opposite ends of the political spectrum. One of the movement’s more prominent activists is Benno Büeler, a former Green . He admits he became disillusioned with the party and decided that a more radical approach was needed to achieve his environmental aspirations. “I was naïve. I thought, we are all people who are blessed with common sense and that wee don’t all have to consume more,” he told Germany’s Suddetusche Zeitung newspaper.

The movement has given a new political home for ex-Greens like Mr Bueler and the likes of Hans Geiger, a 71-year-old former Zurich University economics professor and Credit Suisse director.

Mr Geiger, who is known as “Mr Ecopop” uses the Nazi term Lebensraum (Living space) when discussing ecological issues. He argues that the economic problems Ecopop’s anti- immigration policies might create would be more than offset by improvements in Switzerland’s quality of life.

Balthasar Glattli, a Green politician and one of Ecopop’s most vociferous critics is the author of a book called “The weird ecologists” which he wrote about about the movement last August when it was still relatively unknown. “Ecopop contains everything from eco- conservatives to xenophobes,” he says

Unlike February’s poll, this time around, all of Switzerland’s major parties including the populist right wing SVP, have joined forces to oppose Ecopop. “They are going too far,” admits Toni Brunner, one of the SVP leaders. Economics Minister Johann Schneider-Ammann warns that an Ecopop victory would be a “total disaster” for Switzerland,“ I am afraid,” he says.