The Republic of Ireland and the EU have agreed a financial rescue package, Irish PM Brian Cowen has confirmed.
The Taoiseach said the amount and terms would be negotiated in the coming days with the EU and the IMF.
Irish Finance Minister Brian Lenihan said the amount would be less than 100bn euros (£85bn; $136bn). The UK and Sweden have also offered direct loans.
The crisis has been brought on by the recession and the almost total collapse of Ireland's banks, analysts say.
Markets appeared to react well to news of the bail-out, with the euro strenghening and most Asian stocks trading higher on Monday.
Once known as the Celtic Tiger for its strong economic growth - helped by low corporate tax rates - a property bubble burst, leaving the country's banks with huge liabilities and pushing up the cost of borrowing for them and the government.
Mr Cowen said the government would be publishing a four-year budget plan that would restructure the banking industry.
EU Finance Commissioner Olli Rehn, speaking in Brussels, said the loans would be provided to Ireland over a three-year period and the assistance would help preserve the stability of the eurozone - the group of 16 nations using the euro as their common currency.
Reuters news agency quoted senior EU sources as saying the loans would total 80-90bn euros.
Mr Cowen said the Irish Republic's banks would be made smaller, as part of a restructuring of the banking industry.
The other part of the bail-out package would help to reduce the government's budget deficit to a target of 3% of GDP by 2014, Mr Lenihan said.
Under the bailout scheme, income tax will increase but the country's low 12.5% corporation tax - controversial for some other countries but "non-negotiable" for the Irish government - will not be touched.
It is a sign of the crisis facing the Irish Republic and some of the other highly-indebted European nations that the rescue plan had to be announced late on Sunday, before the financial markets opened on Monday, without many important details having been worked out, says BBC Europe correspondent Jonty Bloom.
The global financial crisis has dealt the Irish Republic a hard blow.
The government has responded with deep spending cuts and costly bail-outs of the banking sector.
Announcing the bail-out on Sunday, Mr Cowen appealed for public solidarity.
"To the Irish people I say simply this: We should not underestimate the scale of our economic problems, but we must have faith in our ability as a people to recover and prosper once more," he said.
"The task of rebuilding our economy falls to our own efforts as a people," he told a news conference following a cabinet meeting on the rescue plan.
"That is where the focus of our efforts must turn over coming weeks, beginning with the four-year plan and then the budget. And now we need to show the solidarity in our own country that our neighbours have shown to us at this time."
Although the country's government claims to be fully funded until the middle of next year, it has provided a blanket guarantee to the Irish banks, some of whom are now finding it impossible to borrow money in the markets.
On Thursday, Mr Cowen's government admitted for the first time that it may need outside help.
Previously the government had said it did not need any financial support from the European Union and IMF.
EU officials fear Ireland's financial problems might spread to other eurozone countries with large budget deficits, such as Spain and Portugal.
The EU and the IMF launched a 110bn euro rescue programme for Greece in May after the government was faced with the prospect of bankruptcy.
Big government spending cuts sent large numbers of Greeks onto the streets in protest.