Greece's leftist government tried on Wednesday to contain a rebellion in Prime Minister Alexis Tsipras' Syriza party ahead of a vote in the evening on reforms required to start talks on a rescue deal.

A first set of reforms that focused largely on tax hikes and budget discipline triggered a rebellion in Syriza last week and passed only thanks to votes from pro-EU opposition parties.

The bill lawmakers will vote on late on Wednesday covers rules for dealing with failed banks and speeding up the justice system - two more conditions set by the euro zone and IMF to open negotiations on an 86 billion euro rescue loan.

The legislation is all but certain to pass, despite planned protests, after opposition parties said they would back it.

But with divisions in Tsipras' leftist Syriza party laid bare by last week's rebellion by 39 deputies, Wednesday's vote will be closely monitored to see if he loses even more support.

"We are making an effort to have fewer dissenters," Health Minister Panagiotis Kouroumplis told Greek TV, while Finance Minister Euclid Tsakalotos said it was crucial that parliament backed the deal so bailout talks could start on Friday.

But hardline Left Platform lawmakers from the Syriza party, who opposed last week's bill, said they rejected this week's law as well.

"A fast-track parliamentary debate and voting process of a bill which exceeds 900 pages has the taste of the most anti-democratic practices," they said in a statement, published on their website Iskra.gr.

Tsipras himself, who is associated with the moderate wing of his party, has publicly said he disagrees with measures demanded by Greece's euro zone peers and the IMF for talks to proceed on a third bailout to save the country from bankruptcy.

But after he made a U-turn by accepting a deal at the 11th hour to keep his country in the euro, he told party hardliners on Tuesday that they should face reality and back the package.

Together with his coalition partners from the right-wing nationalist Independent Greeks, Tsipras has 162 seats in the 300-seat parliament. But last week's rebellion cut his support to just 123 votes and government officials have said elections are likely in the autumn.

"We might go to elections, when this is needed," government spokeswoman Olga Gerovasili told a local radio, adding that this would not be helpful right now as the country prepares to negotiate the new bailout deal. "We are trying to bring the situation back to some sort of normality," she said.