The Swiss Business Federation said on Tuesday that Switzerland should not join the European Union, as this would slow down the country's economy.
"Signing up to the 25-member club will complicate the forging of national economic and social policy," the Zurich-based federation said at a news conference.
It added that if Switzerland were to join the EU, its national finance and fiscal policy would need to be overhauled, and the labor market would also suffer from the new conditions imposed on it.
The federation stressed its support, however, for strengthening bilateral relations between Bern and Brussels.
The bilateral route was not without its pitfalls, but that was the right way forward, the federation said, adding that it considered the bilateral approach a flexible one, enabling a practical cooperation between Bern and Brussels.
The Swiss Businesses Federation is the largest umbrella organization representing the Swiss economy. It has the support of more than 30,000 businesses of all sizes, employing a total of 1.5 million people in Switzerland.
The federation's stance came a day after Swiss Foreign Minister Micheline Calmy-Rey signed a memorandum of understanding on Bern's financial contribution to the EU's newest member states.
On the same day, the EU's Council of Ministers ratified bilateral accords with Switzerland concerning the extension of the free movement of people to the new EU states, film promotion and environment.
The EU is Switzerland's largest trading partner. Besides, over 800,000 EU citizens live and work in Switzerland, and many more cross the borders or travel through the country on a regular basis.
Before the summer, the Swiss government plans to publish a report on relations between Switzerland and the EU.