Photo: Protesters clash with police in some of the worst violence in Greece in years. (Reuters: Yannis Behrakis)
Greek anti-austerity protesters have hurled dozens of petrol bombs at police in front of parliament ahead of a key vote on a bailout deal, in some of the most serious violence in over two years.
Riot police responded with tear gas, sending hundreds of people fleeing in central Syntagma Square.
Earlier, thousands took to the streets of Athens in a series of otherwise peaceful marches during the day to protest against the new bailout deal that saved Greece from bankruptcy but will impose more reforms on a country already deep in crisis.
Once a common sight in protest marches in Greece, clashes with police had been very rare since the leftist Syriza party came to power in January.
Just before the clashes, protesters marched waving banners reading "Cancel the bailout!" and "No to the policies of the EU, the ECB and the IMF".
Pharmacists pulled down their shutters across Greece and civil servants walked off their jobs in protest in a 24-hour strike against reforms.
The split widened in prime minister Alexis Tsipras's Syriza party with Greece's deputy finance minister Nadia Valavani resigning in protest at the reform proposals being put forward.
"I'm not going to vote for this amendment and this means I cannot stay in the government," Ms Valavani told reporters. She submitted her resignation in a letter to prime minister Alexis Tsipras.
The Syriza party is deeply divided over four bills that have to be adopted by Greece's parliament if the bailout, worth up to 86 billion euros, is to be secured.
Photo: Deputy finance minister Nadia Valavani resigned in protest over the reform proposals. (AFP: Louisa Gouliamaki)
The reforms — including sweeping changes to taxes, pensions and labour laws — are seen as likely to pass with the help of the opposition, but the rebellion within Syriza risks having serious repercussions on Mr Tsipras and his government.
The ruling Syriza party, elected in January on an anti-austerity platform, has been deeply split by the bailout deal.
More than half of the party's 201-member central committee, signed a statement rejecting the "humiliating" terms of the bailout, saying it was not compatible with the principles of the left.
"This proposal cannot be accepted by the people of Syriza," they said.
Around 30-40 Syriza lawmakers are likely either to abstain or vote against the government, raising a question mark over how long Mr Tsipras can remain in office.
Speaking to Syriza lawmakers before the vote, Mr Tsipras warned he would need the support of his party to stay, a government official said.
"I am prime minister because I have a parliamentary group that supports me. If I do not have its support, it will be difficult to be prime minister the day after," he told the lawmakers, according to the official.
With pro-European opposition parties set to back the bailout, the measures are expected to pass.
Tsipras appeals to his MPs to 'preserve unity'
Mr Tsipras appealed to his politicians to "preserve unity" in the vote, the state news agency ANA said.
In a closed-door meeting of Syriza politicians, Mr Tsipras said the government "had an obligation to avoid a serious worsening of the humanitarian crisis and economic disaster", ANA said.
Ahead of the vote, the European Commission threw a temporary lifeline to Greece, proposing to give it a three-month 7 billion euro bridging loan through an EU-wide crisis fund until its new bailout is ratified, despite resistance from Britain and Germany.
While it waits for a bailout deal sealed on Monday to kick in, Athens desperately needs money for several imminent payments, including 4.2 billion euros owed to the European Central Bank.
Announcing the plan, Valdis Dombrovskis, the commission's vice-president for the euro, said Brussels was trying to address the concerns of member states like Britain that are not part of the single currency.
British prime minister David Cameron insisted that his country would not be responsible for bailing out Greece, echoing comments by finance minister George Osborne who said the plan was a "complete non-starter".
In France, MPs overwhelmingly backed the bailout agreement, with prime minister Manuel Valls saying it was the only route out of the crisis.
"There can be no 'Grexit', nor 'temporary Grexit' — an old, absurd and dangerous idea," Mr Valls said.
Mr Tsipras returned from Brussels on Monday after striking a deal with his Eurozone counterparts.
He defended the deal saying although it had been "a bad night for Europe" and "imposed" on Greece, the agreement saved it from exiting the euro and must be implemented.
"After five years of salary cuts and harsh measures the Europeans still want more," said Stavros Koutsioubelis, a spokesman for the ADEDY public sector union, urging MPs to reject the deal.
Unions, but also MPs in Mr Tsipras' leftist Syriza party, chafe at a raft of tax hikes and pension reforms that must be passed in the vote if bailout talks with international lenders are to start.
"There was a different program before the election so the measures should not be approved, and if they are approved they should not be implemented," said 40-year-old civil servant Christos Vagenas, who had voted for Syriza in January.
Photo: Protesters marched against austerity in central Athens ahead of the vote. (AFP: Andreas Solaro)
Analysis: Correspondent Mary GearinThere's widespread speculation that a big number of Syriza MPs will vote against the bill. In fact, in the last little while there was a declaration from not (only) the members of the parliamentary party of Syriza but the central committee of the political party, 109 of the 201 central committee members are calling it a coup.
Only a handful of those people are MPs in the parliament but that just gives you some taste of the anger and the frustration that's within the party, within the Greek people themselves.
If they don't pass this bailout deal then it's quite likely that Greece will slip out of the Eurozone and vast majority of Greeks do not want that. On the other hand, they also did not vote for austerity measures.
This same PM asked them to go and vote in a referendum to confirm that, they did and yet he turned around to put this vote through so no matter what, Alexis Tsipras is in a very tricky situation.
Even if these measures are passed, depending on the number of defections it could very well mean that his own position is very much in threat and at some point a caretaker government to take over the rest of the implementation of the deal if it passes.
A snap election is quite likely. If the deal doesn't pass, then of course it puts Greece into all sorts of trouble.
There was great good will towards Mr Tsipras and the Syriza Government in general.
The popular sweep that took them to power in February very much was outside the normal ranks of those who would potentially vote for a Coalition of far left parties.
But there is anger now that Mr Tsipras has gone back to the parliament with a deal that they voted against in that referendum.
It's a volatile situation, although Greeks are pessimistic and potentially resigned to their fate almost no matter whether it be staying in the Eurozone or slipping out of it, that popular support that Mr Tsipras has changed and will potentially be changing very quickly over the next few weeks.
The PM got on to TV last night and said the banks would only open when the sanctioning of this deal came through and that it could take a month.
From other news sites: