Eurozone leaders have been urged to "do what it takes" to ensure the stability of the single currency at emergency talks in Brussels on Thursday.
The plea from European Commission (EC) president Jose Manuel Barroso reflects fears that speculators will pounce if the latest in a series of economic summits fails to restore euro credibility and halt "contagion" to other struggling member states, including Ireland, Portugal and Italy.
"Nobody should be under any illusion: the situation is very serious. It requires a response - otherwise the negative consequences will be felt in all corners of Europe and beyond. They have said they will do what it takes to ensure the stability of the euro area. Well, now is the time to make good on that promise," said Mr Barroso.
The latest summit was demanded by the French but opposed by Germany and other countries concerned that more inconclusive talks will only worsen the market response. Chancellor Angela Merkel said she would only attend if a positive result was assured.
But as the leaders of the eurozone countries prepare to meet, there was little sign of full agreement on a second bail-out package for Greece - this time to include a financial burden on private bondholders as well as taxpayers in the event of default.
Irish Prime Minister Enda Kenny, attending the talks, called for tough decisions to be taken to stop the Greek debt crisis spreading to Spain and Italy - both in the queue for possible bail-out help following massive cash injections to Ireland and Portugal.
Mr Kenny, keen to negotiate a lower interest rate on Ireland's crippling repayments, said: "I do hope that what comes out of the meetings will be the start of a series of decisions taken by the eurozone leaders which will restore confidence, restore certainty, deal with the issue of the legitimate anxiety and concern about contagion spreading from the Greek situation, which simply has to be dealt with."
French finance minister Francois Baroin said the summit had to take decisions on a second bail-out for Greece to makes its debt "more bearable".
The problem is German insistence that private investors should extend deadlines for loan repayments as part of any new 120 billion euro bail-out to be triggered next year.
The European Central Bank says that extending credit lines would amount to a Greek default, prompting more market jitters about the single currency's long-term prospects.