Thousands of anti-austerity protesters in Athens have clashed with police as MPs debate whether to approve an €86 billion Eurozone bailout deal.

Demonstrators marched through the city centre while civil servants staged a 24-hour strike that disrupted public transport nationwide.

As the protests turned violent, hooded demonstrators hurled petrol bombs at riot officers outside the Greek parliament, where politicians are preparing to vote on a series of painful reforms aimed at saving their economy from collapse.

Riot police used pepper spray and tear gas to deter protesters who were throwing rocks at officers.

There were also angry scenes in parliament as deputies discussed approving the new measures, which include tax hikes and pension cuts aimed at securing the eurozone loan.

Greek Prime Minister Alexis Tsipras faces a revolt within his own Syriza party as he battles to win the parliamentary vote on the bailout, which depends on more austerity measures for the next three years.

Rival Golden Dawn MP Ilias Kasidiaris ripped up his parliamentary papers in disgust and threw them across the chamber.

Earlier, the deputy finance minister Nadia Valavani resigned from Prime Minister Alexis Tsipras' government in protest.

The vote comes after one of Greece's major creditors cast doubt over whether the overall package of measures - which includes a foreign takeover of state-owned businesses - would be enough to ensure the country recovers.

The International Monetary Fund (IMF) said Greece has taken on too much debt and will be unable to keep up its repayments even after the new deal. It said Greece's debts will peak at 200% of the country's economic output in the next two years.

The organisation said the only way Athens could emerge from the crisis was if some of its debts were restructured - possibly by extending the period of repayment or even by writing off some of them.

Defending the terms, Tsipras said the 'bad deal' was the best available option under the circumstances.

"I assume responsibility for all mistakes I may have made, I assume responsibility for a text I do not believe in, but which I signed to avoid disaster for the country, the collapse of the banks," he said.

Tsipras also predicted that 'the great majority of Greek people' will support the deal, but admits he 'cannot say with certainty' that it will be enough to stop Greece exiting the eurozone - a so-called 'Grexit' - until the final bailout agreement is signed.

Austerity measures being put to the Greek parliament include an increase in VAT on all goods and services; ending the VAT reduction for the Greek islands and a series of other tax rises and mMaking the Greek statistics office independent and introducing a mechanism that automatically restrains spending if it gets too high.

These are the first of a series of laws that will have to be passed before the bailout will be fully approved. The bill is expected to be passed, but only with support from opposition parties. In order to become law, the vote has to be passed by midnight Greek time, 10pm UK time.

Greece's finance ministry said the banks - which have been shut since 29 June - would remain closed until at least Thursday, (16 July ) but some would open to allow payments to the state.