The threat to Austria from its EU partners that it will face diplomatic sanctions if the far-right Freedom Party (FPO) is brought into government yesterday won backing from the US, several accession states of eastern Europe and the European Commission.
The threats came just hours before a press conference announced that agreement had been reached between Mr Haider's party and the conservatives, who between them have 104 seats, on a deal for a coalition government.
Neither party has received a mandate from the Austrian President, Mr Thomas Klestil, to form a government, as required by the constitution. Mr Klestil, who has in effect been slighted by their decision to start negotiations on their own initiative, had said he would await the outcome of their talks before making a decision.
"I fear that the number of those in Austria who favour such a government has increased since the threat of sanctions," the Austrian ambassador to France, Mr Franz Ceska, said yesterday.
The leader of the conservative People's Party (PP), Mr Wolfgang Schussel, said negotiations with the FPO, whose leader, Mr Haider, will not himself join the new government, would be completed by today.
Mr Schussel, who is also acting foreign minister, told reporters he took seriously international worries about the prospect of the FPO entering government.
But he said the best way to counter this was to present a "reasonable government programme".
He added that it would be dangerous for the EU if the principle became accepted that the presidency could issue statements on behalf of just 14 member-states instead of all 15.
Meanwhile, the US said it would review its relations with an Austria governed by a coalition including the FPO.
The National Security Council spokesman, Mr David Leavy, said: "Should this occur we would examine carefully the range and depth of our bilateral relationship, and consider similar steps to those identified by the Europeans."
And the European Commission met in emergency session to review the move, issuing a statement that drew attention to the Amsterdam Treaty provisions for suspending the membership of a state in "persistent and serious" breach of fundamental rights.
Although the commission would at present continue to treat Austria as any other state, in line with its treaty obligations, "we fully share the concerns underlying the decision by the 14", its President, Mr Romano Prodi, said.
A statement made it clear that the threatened boycott of bilateral meetings would not affect the EU institutions.
The German Chancellor, Mr Gerhard Schroder, insisted: "If we make it clear that we want nothing to do with politicians like Mr Haider, that is not interfering in another country's affairs. "It is an expression that we stand for a Europe based on values and that Mr Haider has constantly violated those values."
Italy's Prime Minister, Mr Massimo d'Alema, said the EU had a duty to intervene in the affairs of a member-state to fight racism and protect fundamental human rights.
Speaking through a spokesman after being hospitalised with a viral infection, President Vaclav Havel of the Czech Republic said he understood the need for the ultimatum, and that the Union could not stand by and allow dangerous extremism to grow unchecked.
"The European Union is a union of values and not simply a geographic union," the Hungarian Foreign Minister, Mr Janos Martonyi, said.
"These standards and values are valid for both EU members and EU candidates."
Mr Haider is openly against the countries' rapid integration into the EU, once famously declaring that EU enlargement was a "declaration of war" on all working Austrians, whose jobs, he said, were at risk from cheap foreign labour.
Some diplomats contacted yesterday said concerns that the FPO would seek to block enlargement may well have been what triggered the unprecedented action by the 14.
Others were more inclined to see the move as largely "value-driven" in an international climate which increasingly supports the idea that fundamental rights concerns should supersede preoccupations with national sovereignty.
Diplomatic sources said the move was pressed particularly by Belgium and France, with most support coming from the UK, Germany, Italy, Sweden and Greece.
But a British source said there was some nervousness among British ministers about the precedent being created.
And an Irish source said: "We're not exactly going hell for leather on the issue".
Within the European Parliament the Munster MEP, Mr John Cushnahan, has initiated moves to expel the PP from the largest group, the EPP, if it goes into coalition with the FPO. In a letter to the group leader he says such an alliance would be a "betrayal of fundamental Christian Democrat values".
