Resolving the European financial crisis is the most important task for world leaders, the US President Barack Obama has said at the G20 summit in Cannes.
Mr Obama said the EU had taken steps towards a solution, but more details were needed about how the plan will be "fully and decisively implemented".
As the G20 leaders begin talks, the Greek Prime Minister George Papandreou is due to meet the country's president after holding emergency talks with his cabinet in Athens.
He is facing a rebellion from ministers over plans to hold a referendum on the bailout - after France and Germany warned Greece it wouldn't get more rescue funds until after the vote.
Finance minister Evangelos Venizelos said Greece's euro membership "cannot depend on a referendum" and that the next bailout funds should be released "without any distractions or delay".
Mr Papandreou is also facing calls to resign, and a small group of MPs (BSE: MPSLTD.BO - news) from his own party are reportedly preparing a proposal for a coalition government headed by former European Central Bank vice president Lucas Papademo.
French President Nicolas Sarkozy, who is hosting the meeting in Cannes, said: "We said clearly to the Greek authorities that the EU, like the IMF (Berlin: MXG1.BE - news) , cannot envisage paying the sixth tranche until Greece has adopted the package and all uncertainty has been lifted.
"We cannot commit the money of taxpayers ... until the rules that were agreed on October 27 are respected. Without that, neither Europe (Chicago Options: ^REURUSD - news) nor the IMF can pay a single cent."
Stock markets across Europe saw early falls following the announcement, but later reversed losses.
European leaders agreed a deal last Thursday that would see banks accept a 50% writedown of Greece's debt, higher than the 40% they had originally offered.
It would also increase the scope of the 440bn euro (£386bn) bailout fund to around 1trn euro (£876bn).
As he arrived in Cannes for the summit, the Prime Minister David Cameron once again said the UK was not prepared to contribute to the rescue fund - either directly or through the IMF.
However, he did say Britain was ready to consider boosting its contribution to the IMF's lending facilities for individual countries in financial crisis - which could include Ireland (Xetra: A0Q8L3 - news) , Portugal or even Italy.
George Papandreou's decision to put the deal to the people sent stock and bond markets across the world falling earlier this week.
Speaking after emergency talks with Sarkozy and German Chancellor Angela Merkel on Wednesday, Mr Papandreou said he was confident that his people would accept the EU bailout plan in the vote set for December 4.
"I believe the Greek people are wise and capable of making the right decision for the benefit of our country," he said.
"We are part of the eurozone and we are proud to be part of the eurozone."
The Greek government now faces a key confidence vote expected in parliament on Friday, which may see Mr Papandreou struggle for survival.
Major Asian economies have also warned Europe to tackle the crisis before it has a serious impact on economies elsewhere in the world.
China's deputy finance minister Zhu Guangyao said: "Like our European friends, we did not expect the Greek (call for a) referendum. It was an independent decision taken by Greece. I hope this period of uncertainty would be contained."
The White House said US President Barack Obama wanted "unanimity of purpose" to emerge from the G20 and White House spokesman Jay Carney said the situation would be a key subject.