The Greek parliament has passed new austerity measures, including increases to sales taxes and an extension of the retirement age, demanded by European creditors.

The first stage of the bailout package was passed by a comfortable majority of Greek MPs as riot police restrained demonstrators outside the parliament.

However, in a symbolic act of defiance by Greek parliamentarians, the measures were not approved by the July 15 deadline stipulated under the bailout deal.

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The bills, introduced by Prime Minister Alexis Tsipras on Tuesday, were not passed until after 1am (Brussels time) on Thursday.

A total of 229 MPs in the 300 seat parliament supported the motion, while 64 voted against it.

Mr Tsipras’ future as prime minister is up in the air after a large block of MPs from his ruling Syriza party voted against the new measures.

At least 32 Syriza MPs voted against the motion and six abstained.

Greek prime minister Alexis Tsipras said he didn’t like the austerity deal, but he had accepted it.

Former finance minister Yianis Varoufakis was among the Syriza members who voted “No”.

Mr Tsipras was able to ram through the fiscal reforms with the support of opposition parties, including the conservative New Democracy party.

The debate will go down as one of the most significant and bizarre in Greek political history after Mr Tsipras admitted that he did not believe in the bailout package.

The prime minister argued for the new bailout proposals to be implemented because he said there was no other way to lift Greece out of its debt mire.

However, New Democracy leader Evangelos Meimarakis said the government had mishandled the negotiations with European creditors and needed to explain why it had not been able to negotiate a haircut on the nation’s €320 billion debt.

At a special party meeting on Wednesday morning, Mr Tsipras said it would be difficult for him to continue as prime minister if party members lodged a large protest vote in the parliament.

Support for Mr Tsipras has fragmented among members of his cabinet after the deputy finance minister Nadia Valavani resigned on Wednesday morning.

“I’m not going to vote for this amendment and this means I cannot stay in the government,” she told television reporters.

Mr Tsipras appealed to parliamentary members to back the measures, saying the Syriza government had fought courageously against financial powers of Europe.

He highlighted Greece’s decision after World War II to forgive Germany’s financial debts and assured that it would soon become clear to Greek citizens that the reign of corporate oligarchs in Greek society was over.

Mr Tsipras promised to launch a crackdown on corruption and tax evasion and told the parliament that he had accepted the bailout package with a heavy heart.

The president of the Greek parliament, Zoe Konstantopoulou, a Syriza hardliner declared the bailout package was an attack on Greek sovereignty.

“There is no doubt the government is being blackmailed,” she said.

She warned that if the measures were passed other debtor countries would face similar attacks on sovereignty.

Earlier during the debate, representatives of the fascist Golden Dawn party called on Greeks’ love of honour to bin the bailout package.