Inside the bar an equally curious event is taking place. It is a rally of two dozen young Conservatives fighting a rearguard action to prevent Switzerland voting to become the 190th member of the United Nations in a referendum next Sunday.

They are undaunted by the fact that since the tiny Pacific atoll of Tuvalu joined the UN two years ago, Switzerland and the Vatican state are the world's only non-members.

Neither does it matter that another Swiss city, Geneva, hosts the UN's European headquarters and eight of its agencies; that Switzerland already pays Fr500 million (£200 million) a year to support the UN's humanitarian work; or that its Government invariably follows the UN's lead on global issues. The young Conservatives are determined to preserve Switzerland's legendary neutrality, whatever the cost.

"We put the freedom and independence of our country before everything else," said Toni Brunner, a member of Christoph Blocher's populist, right-wing Swiss People's Party (SPP) and, at 27, his country's youngest MP. "If we join the UN, we have to sign a binding charter whereby we have to do what the big powers want."

Monika Lienert, another speaker, said: "We are told to show courage and join. Isn't it more courageous to be the only country that stands aside?" The rally ends with a unanimous vote against membership of an organisation whose five-member, US-dominated Security Council would compel Switzerland to implement UN sanctions and embargoes.

The Swiss rejected UN membership overwhelmingly in 1986, when 75.7 per cent of its seven million people and all 26 cantons voted against. But that was when the UN was still polarised and paralysed by the Cold War's East-West enmities and there was good reason to stay out.

Today the circumstances are very different: the Cold War is over; the UN is functioning again; Switzerland's multiparty Government argues that in a fast-changing world there is no longer an international role for an independent outsider. The country's self-imposed isolation is also beginning to hurt it politically and economically.

Almost the entire Swiss political establishment, the country's business leaders, its newspapers and even Zurich's celebrated bankers now favour membership. Dr Blocher's SPP is the lone dissenting voice.

Dr Blocher's antipathy should not be underestimated. The billionaire industrialist is his country's most charismatic politician. His party is Switzerland's biggest, with a quarter of the national vote. His "no" campaign is spending heavily on advertisements showing the word "neutrality" being severed by an axe, quoting articles from the UN charter committing member states to collective action and asking: "Who stands for peace if the UN itself is waging war, if the UN is a servant of the big powers?"

This time, however, opponents of UN membership are outgunned by the "yes" camp, which has the Government's wholehearted backing and is being funded by Economiesuisse, the Swiss trade organisation that has promised to spend "as much as it takes" to win. It is shaping up as one of Switzerland's most expensive referendums, with the two sides expected to spend at least £8 million between them.

Andreas Gross, the Social Democrat MP who organised the collection of the 100,000 signatures required to trigger a referendum, said: "We have to be where the world tries to solve its common problems. Switzerland is perceived as an egotistical country that only looks to itself."

He added that Switzerland's aloofness was hurting it economically. The country had much to contribute to the UN and the world, but could not do so if it remained in splendid isolation.

The "yes" campaign's posters urge the Swiss to "Flagge Zeigen" (Show the Flag), and they seem to be working. The latest poll shows that 54 per cent of the population intend to vote yes. The "no" campaign's best hope rests in the fact that approval of the referendum requires a majority not only of the popular vote, but of the cantons and several of the smallest remain firmly in Dr Blocher's camp.

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