Geneva's taxi drivers have blown a gasket over a ruling that will allow French cabbies to ply for trade in the canton.
Claiming that the move amounts to unfair competition, the Geneva Taxi Drivers Union has warned of confrontations between drivers and the possibility of strike action.
On Wednesday the local government adapted the law on taxis and limousines to bring the canton into line with recent changes to labour market regulations.
From now on taxi drivers from the EU and Switzerland will enjoy the same rights as those in Geneva and can pick up bookings across the canton.
Up until now around 150 French taxis registered in the neighbouring departments of Ain and Haute-Savoie have been allowed to pick up clients at the city's airport, which lies on the border between France and Switzerland.
Wednesday's decision provoked a predictably furious response from many of the canton's estimated 1,000 cabbies.
"It's fair to say that this decision has not gone down well," Severino Maurutto, president of the Geneva Taxi Drivers Union, told swissinfo.
"This represents a real threat to the livelihood of taxi drivers in Geneva, who are already suffering due to a surplus of taxis."
Maurutto said the canton already had 200-300 cabs too many and the prospect of hundreds more joining the fray was "unthinkable".
He said all the various Geneva taxi associations were due to meet early next week to formulate a response, adding that he could not rule out strike action.
"The fundamental problem is one of unfair competition. Petrol is cheaper in France, as is the standard of living, and as a result the cost of hiring a cab is less than here," said Maurutto.
"Our fear is that French taxi drivers, and those from other cantons, will come to Geneva and cut deals with the hotels and international institutions."
Maurutto claimed up to 600 French cabbies already worked illegally in Geneva, causing friction between drivers from the two countries, especially during the winter ski season, Easter and the summer months.
"There were a few clashes a number of years ago and we had to take steps to calm the situation, but this decision is likely to stir things up again," he said.
Benoît Roulin, a senior cantonal official, declined to comment on the taxi drivers' grievances but said the local government had no choice but to comply with the recent opening up of the Swiss labour market.
Geneva's taxi drivers have a reputation for mounting the barricades. Last year they staged a two-hour strike at the city's airport after the cantonal authorities decided that all cabs should be painted yellow by 2010. It is one of a number of measures contained in a new taxi law that has angered drivers.
swissinfo, Adam Beaumont in Geneva
A bilateral accord opening up the Swiss labour market to workers from the European Union came into force in 2002. Voters agreed to extend this to include the ten new EU members in September last year.
According to the Federal Statistics Office, around 180,000 cross-border workers are employed in Switzerland – 55% come from France.
The number of those working in the Lake Geneva region has almost doubled over the past five years and stood at 58,200 at the end of March.
In July this year the government lifted restrictions that had made it difficult for Swiss registered in one canton to work in another.