Swiss voters are to decide this weekend whether to open the country's borders to Romania and Bulgaria amid a racially-charged political debate.
Posters showing sinister black crows pecking away at a map of Switzerland have added controversy to Sunday's referendum on whether to extend the country's free movement agreement with European Union.
The stark imagery has been used by the right-wing Swiss People's Party, or Schweizerische Volkspartei (SVP), in a repeat of the controversial racial imagery that made it Switzerland's largest political grouping during elections last year.
The latest SVP poster echoes its Oct 2008 campaign image which played on popular resentment of immigrants by showing a group of white sheep kicking a black sheep off a Swiss flag.
Alain Hauert, spokesman for the SVP, admitted that the black crow poster, captioned "Free passports for all? No", did aim to target popular fears of being swamped by mass immigration from Romania and Bulgaria, the EU's poorest countries.
"The enlargement of free movement to Romania and Bulgaria is a threat. Our unemployment is rising and our social insurance is under pressure. Wages in Romania and Bulgaria are 15 times lower than here. Big companies will look for cheap labour from Romanians and Bulgarians and this is a real threat," he said.
Mr Hauert insisted that the black crows also represented Germany, Switzerland's big EU neighbour and Berlin's pressure on secretive Swiss banks to reveal the names of account holders to German tax inspectors.
"Germany is placing huge pressure on Swiss banks to give up personal data. That is a big problem for our country that the crows represent too," he said. "It has nothing to do with race."
The tide of Swiss public opinion might be turning against open borders with the EU.
Nine years ago 67 per cent of Swiss voters backed the first free movement agreement with the EU.
In 2004, as the EU enlarged eastwards referendum support for a second treaty dropped to 54 per cent.
Current opinion polls show that only 50 per cent back the new EU deal, with 43 per cent opposed and seven per cent undecided.
Adrian Sollberger, chief of information at the Federal Department of Economic Affairs, is concerned that the global economic recession might push Swiss voters into a protectionist referendum rejection.
"It doesn't help that we are facing an economic crisis now and unemployment rates are rising," he said.
The Swiss government, most political parties and business organisations have stressed that extending the free movement agreement with the EU is vital for the country's economy.
Almost two thirds of Swiss exports flow into the EU and 20,000 trucks cross its borders every day in trade that is eased by existing open borders agreements.
If Swiss voters reject the free movement agreement, the EU is entitled, within in six months, to suspend all previous border arrangements with Switzerland, a sanction that could make business more complicated and costly.