Greece's creditors will head to Athens shortly to begin talks on a mammoth new bailout, the government said Thursday, as parliament approved a second batch of reforms needed for the negotiations to proceed.

Greece's finance ministry said representatives from the European Union, European Central Bank and International Monetary Fund, from whom Athens is seeking a third bailout worth up to 86 billion euros ($93 billion) over three years, were likely to fly in on Friday.

But a European source said it was not yet confirmed that the talks would begin Friday, adding that at most "only a few people" from the so-called troika of creditors would arrive before the weekend. "Our people haven't bought their airline tickets yet," the source said.

Greece and its creditors last week struck a bailout deal aimed at preventing Athens from crashing out of the eurozone as it struggles to pay its enormous debts.

But the IMF warned on Thursday that finalizing the deal, which is conditioned on Greece implementing painful reforms, would not be easy.

The IMF has helped bail out Greece twice previously but has said it will only participate this time around if European creditors reduce Athens' debt burden to a level it considers "sustainable".

"Clearly it's a difficult path ahead, we're just at the beginning of the process," said IMF spokesman Gerry Rice.

In the early hours of Thursday, the Greek parliament passed further reforms demanded by creditors for bailout talks to begin, including changes to the justice system, a bank deposit protection scheme and measures to shore up the liquidity of Greece's banks.

Greece and its creditors are under huge pressure to finalize the terms of the rescue before August 20, when Athens is scheduled to make a loan repayment of 3.2 billion euros to the ECB that it cannot currently afford.

The bill passed by a resounding 230 votes out of the 298 members of parliament present, after a five-hour debate that once again exposed deep divisions in the governing Syriza party over whether to accept more austerity.

While the result is a victory for Prime Minister Alexis Tsipras in that he managed to convince parliament to back him on the bailout, he did suffer a major rebellion from Syriza MPs for the second time in a week — prompting analysts to predict he may be forced to call early elections.

Government spokeswoman Olga Gerovassili admitted the government was facing a "political problem", telling reporters after the vote: "The divide in the parliamentary majority is clear."

The latest batch of reforms sparked fiery debate on Wednesday night, with lawmakers clashing into the early hours on everything from Marxism to submarines and the speaker of parliament comparing the bailout deal to "a coup".

In a passionate speech to the chamber, Tsipras argued Greece had to adapt to the "new realities" of the agreement if it wanted to avoid a default on its debts and a messy exit from the euro.

"The painful path does not stop here, unfortunately," he said.

"We were at the limits of our economy and our banking system, and at the limits of Europe — where conservative forces, obsessed with austerity, dominate," he added.

Some 6,000 anti-austerity demonstrators protested near parliament ahead of the debate, with a handful of them lobbing petrol bombs in the direction of the police.

Syriza came to power in January promising an end to the austerity that has battered the Greek economy for years, and some in Tsipras' party believe he has caved to "blackmail" from the creditors in agreeing to more tough reforms.

He had to rely on the support of opposition parties to get the two bills linked to the bailout passed.

Having lost the support of nearly a quarter of his MPs on two crucial votes in the last week, Tsipras could "have difficulty passing laws in future without forging a political agreement with other parties," said Dimitris Sotiropoulos, a political science professor at Athens University.

Tsipras was forced to reshuffle his cabinet last week, sacking three ministers for voting against the first bailout bill.

Gerovassili, the government spokeswoman, previously said the administration had "no intention" of calling early polls.

Tsipras told parliament on Thursday that he would keep fighting for Greece's best interests, adding he would not "voluntarily abandon" the job.