New footage shows protesters hurling petrol bombs at riot police outside the Greek parliament in Athens.
The clashes come as MPs inside the building prepare to vote on a bailout package that would see the country forced to impose a new range of austerity measures.
Police responded with tear gas, sending hundreds of people running from the square and ending the brief violence.
At least 31 protesters have been detained following the clashes, while there are no reports of any serious injuries.
Protesters have been involved in violent clashes with police as a debate on a controversial bailout package gets underway - watch live footage from outside the Greek Parliament:
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Riot police have been pictured tackling petrol bombs thrown at them by protesters as violence erupted outside the Greek parliament.
Protesters and riot police have clashed in a square outside Greece's parliament ahead of a debate on a bailout package for the country.
Petrol bombs were thrown at officers by a small number of anti-austerity demonstrators, while tear gas appeared to fired in an effort to disperse crowds.
The clashes follow peaceful protests earlier in the day over the additional austerity measures due to be included in the deal with Greece's international creditors.
Greece's proposed bailout deal is like the Versailles treaty which led to the rise of Adolf Hitler, former finance minister Yanis Varoufakis has claimed.
Varoufakis, who resigned last week citing complaints from European creditors over his combative style of negotiation, quoted a famous British economist in a statement to MPs that was met by heckling from some areas of the room.
"'The powerful demanded that the losers accept terms they had no right to demand. The losers accepted commitments they had no right to accept'.
"These were the words of John Maynard Keynes on the Versailles Treaty. What we are confronted with is a new Versailles Treaty."
However, he did not say whether he would vote against the proposed agreement, or even if he would attend.
In the 1919 Treaty of Versailles, Germany was forced to pay crippling reparations as the price of defeat in World War One - a factor historians attribute to the rise of Hitler's Nazi party.
Asked earlier this week whether she thought there were similarities between the Greek deal and Versailles, German Chancellor said she would not take part in historical comparisons "especially when I didn't make them myself".
Civil servants and pharmacists in Athens walked out of their jobs today in protest against a proposed bailout deal which would see further austerity imposed on Greece.
Protesters held banners reading "Cancel the bailout! and "No to the policies of the EU, the ECB and the IMF".
Stavros Koutsioubelis, a spokesman for the ADEDY public sector union, said MPs should reject the bailout.
"After five years of salary cuts and harsh measures the Europeans still want more," he said.
However, while a few thousand were seen on the streets, an opinion poll published yesterday found that more than 70% of the public wanted parliament to approve the deal.
Greek Prime Minister Alexis Tsipras is facing increasing pressure from MPs - including many from his own party - as they debate ahead of a key vote on the bailout deal agreed with the country's creditors.
Amid anger over the deal - which requires a new raft of austerity measures - his own deputy finance minister resigned today, saying she could not vote in favour.
Other ministers within Tsipras' Syriza party have also said they will not vote in favour of the measures, while one rival MP from right-wing Golden Dawn party ripped up a copy of the deal in the chamber before throwing it in the air.
Speaking as he tore up the "despicable document", Ilias Kasidiaris said: "They [international creditors] are not going to get anything from Greece and those despicable memoranda to which the Greek people said no will send you and your policy to the rubbish bin of the Greek history."
Former finance minister Yanis Varoufakis also spoke during the debate, calling the deal a "continuation of debt slavery" before one heckler shouted "traitor" and "the man who brought us here".
David Cameron will not commit funds to help bail Greece out because "it is not for Britain to bail our Eurozone countries".
However, he told Parliament, "if Greece were to leave the euro and wanted humanitarian assistance, I am sure that this house and the British public would take a more generous view".
"Sorting out the problems of the eurozone, which we've always warned about, is a matter for eurozone countries."
The prime minister also said that the IMF view that Greece needs debt relief "must be right".
David Cameron believes a solution can be found to provide bridge financing to Greece while not putting British taxpayers' money on the line, a spokeswoman said.
"We have always been clear that British taxpayers' money is not going to be used to provide finance for a euro zone Greek deal and that therefore this is a non-starter," Cameron's spokeswoman said.
"From the discussions that have been taking place this morning, it's clear that a number of other countries have concerns about this. I think there are a number of solutions that can be found."
Spanish Prime Minister Mariano Rajoy says he will put the details of a third Greek bailout to his own parliament for debate and ask for its approval.
Rajoy's People's Party holds an absolute majority in parliament. He did not say when the vote would take place.
"Even though this step is not obligatory in our country, it is my intent to take it to parliament for debate and possible approval (...) because there are a lot of funds that Spanish taxpayers are being asked to guarantee," Rajoy told parliament.
Most eurozone governments will wait until the proposals have been through the Greek parliament before raising the issue at home.