Greece’s government has announced it has reached the outline of a deal for an international bailout worth 85 billion euros ($A126.4 billion) to save its stricken economy from collapse.

The European Commission said Athens and its creditors had reached a technical agreement “in principle” on a bailout – the third for the debt-crippled country since 2010 – after marathon talks stretching into the early hours.

“What we don’t have is a political agreement,” said Commission spokeswoman Annika Breidthardt, hours after Athens suggested the deal was all but done.

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Greece and its creditors – the EU, the European Central Bank, the eurozone bailout fund and the International Monetary Fund – are under pressure to finalise the deal by August 20 when Athens must repay some 3.4 billion euros to the ECB.

The draft agreement comes after months of acrimonious negotiations between the creditors and Greece’s radical-left government, which came to power in January promising an end to years of painful austerity demanded in exchange for the cash.

Investors reacted with relief to news of the outline deal, with shares in Athens closing 2.14 per cent higher after three straight days of gains.

But both sides said details remained to be hammered out, and an EU source stressed it was still not certain that the deal would be finalised by August 20 – leaving open the possibility that Athens might need emergency funding to pay its ECB debt.

The technical agreement has yet to be officially endorsed at the top political level, with eurozone finance ministers likely to meet at the weekend.

Despite the details still to be thrashed out, a Greek government source said Prime Minister Alexis Tsipras had nonetheless pushed ahead Tuesday evening and requested an emergency session of parliament for Thursday – with all lawmakers required to attend – for a crucial vote on ratifying the deal.

Tsipras is under pressure from many in his radical-left party Syriza who say the new accord will pile further austerity on a weakened economy and goes against the party’s campaign pledges.

The embattled prime minister has warned that he may be forced to call early elections if the mutiny continues.

The Kathimerini newspaper said the Greek government would have to immediately implement 35 measures before the deal can kick in.

These include energy market deregulation, changes to shipping taxes, price cuts in generic drugs, a review of the social welfare system and phasing out early retirement, the daily said.
The talks saw Athens committing to a primary deficit of 0.25 percent of output in 2015, and a surplus in 2016, a finance ministry source said.

The government said in a statement that the creditors had agreed to a “mild adjustment” on fiscal targets that will help foster growth and save some 20 billion euros.

It said Greek banks – which were forced to shut down for three weeks as panicked customers withdrew billions of euros – would immediately receive 10 billion euros from the package, and will be fully recapitalised by the end of the year.