Italy's president is considering ways out of an acute political crisis after ex-PM Silvio Berlusconi's ministers left the coalition government.
Giorgio Napolitano hinted that he would try to oversee the formation of a new coalition without calling elections.
This follows weeks of worsening ties between Berlusconi's party and PM Enrico Letta's centre-left grouping.
Berlusconi had already threatened to withdraw his ministers if he was expelled from the Senate for tax fraud.
Analysis
Prime Minister Enrico Letta is among the most mild-mannered of Italy's politicians.
And that makes the ferocity of his response to Mr Berlusconi's manoeuvre all the more striking.
Mr Letta described the reasons given for the resignation of the ministers as a "huge lie".
So there's no going back. This most awkward and unhappy of coalition governments is finished.
Now President Napolitano will become a key player.
Constitutionally it is down to him to decide whether Parliament should be dissolved.
And fresh elections are a possibility.
But President Napolitano would probably do all that he could to avoid the protracted instability of an election campaign - and the prospect of another inconclusive result.
So there may well now be a major effort to try to stitch together some new coalition from within the existing parliament.
The current coalition government was put together after inconclusive elections in February, and the latest developments cast a further shadow over Italy's struggling economy, the eurozone's third-largest.
It is feared that the crisis could hamper efforts to enact badly-needed reforms to tackle Italy's economic problems, including debt, recession and high youth unemployment.
The International Monetary Fund has warned that coalition tensions represent a risk to the Italian economy.
'Grave violation'Speaking on Saturday, President Napolitano called for political continuity in the country.
"We need a parliament that discusses and works, not that breaks up every now and then," he said.
"We do not need continuous election campaigns, we need continuity of the government's actions, decisions and its measures to resolve the problems of this country."
Italy is now in very uncertain political terrain, and at times like this its head of state becomes a hugely important figure, the BBC's Alan Johnston in Rome reports.
Later on Sunday, Mr Napolitano is expected to meet Mr Letta, and their talks will be closely watched for the first indications as to how this crisis will play out, our correspondent says.
Mr Letta, of the centre-left Democratic Party, warned late on Friday that he would quit unless his coalition cabinet won a confidence vote due next week.
Silvio Berlusconi's trials
- Accused of having paid for sex with an underage prostitute and of abuse of power for asking police to release her when she was arrested for theft
- Convicted of tax fraud in case focusing on the purchase of the TV rights to US films by his company, Mediaset
- Acquitted in several other cases; also convicted in several, only to be cleared on appeal; others expired under statute of limitations
But Berlusconi pre-empted that, describing Mr Letta's comments as "unacceptable". He later said all five ministers of his People of Freedom (PDL) party were resigning.
The PDL is objecting to a planned increase in sales tax, which is part of wider government policy to reduce big public debts.
Interior Minister and PDL Secretary Angelino Alfano accused Mr Letta of "a grave violation of the pacts that this government is founded on".
But the prime minister responded angrily to the resignations, accusing the PDL leader of telling Italians a "huge lie" in using the sales tax as an alibi for his own personal concerns.
"In parliament, everyone will have to assume responsibility for their actions before the nation."
Berlusconi's legal problems are seen as a cause of much of the tension inside the coalition.
A committee of the Senate decides next week if he should be expelled after the Supreme Court recently upheld his conviction for tax fraud.
It was his first conviction to be confirmed on appeal in two decades of fighting legal cases.
Berlusconi was sentenced to a year in jail, but is expected to serve house arrest or community service because of his age.
