Europe piled pressure on Saturday on banks to write off vast Greek debts, as leaders struggled to come up with a lasting answer for a crisis now threatening the entire eurozone. Amid dire warnings that Europe's debt crisis threatens global recession, ministers put the squeeze on banks to accept write-downs on Greek debt of "at least 50 percent" to allow a new bailout for Athens to go ahead. But a drive for the eurozone's wider rescue fund to tap into unlimited European Central Bank funds hit the rocks, as French President Nicolas Sarkozy and German Chancellor Angela Merkel flew in for crunch talks before back-to-back EU summits on Sunday and Wednesday. Governments remained miles apart on how to boost the firepower of the rescue fund, Dutch Finance Minister Jan Kees De Jager said. A plan long championed by Sarkozy to turn the 440-billion-euro European Financial Stability Facility (EFSF) into a bank that could draw money from the European Central Bank (ECB) "is no longer an option," De Jager said. Merkel and the ECB opposed the idea, and European Union ministers were left looking at two alternative scenarios: using the EFSF to insure partial losses on future eurozone bonds, and getting the IMF to step up its parallel involvement. "Big differences" remain on which road to take, De Jager added. As he and fellow ministers looked at plans to recapitalise banks so they can better withstand the shock of Greek losses, eurozone finance chief Jean-Claude Juncker said lenders had to accept a "substantial increase" on a prior deal for a 21-percent "haircut." Diplomatic sources underlined that Europe and the IMF would only proceed with a second planned Greek bailout of 109 billion euros ($151-billion) if banks accepted losses of "at least 50 percent" on their debt holdings. Banks should not expect "freebies" from taxpayers, said Sweden's finance minister Anders Borg. The EU wants banks to raise their core cash reserves -- so-called "tier-1" capital -- to nine percent, but the idea of forced recapitalisation has been poorly received by the banking community. The European Banking Authority (EBA) has estimated that between 80 and 100 billion euros is needed to restock banks' capital bases. But this figure appears unlikely to reassure jittery markets, since the International Monetary Fund has estimated that at least twice this amount is needed. Greek Prime Minister George Papandreou was also to fly to Brussels for talks with European Commission chairman Jose Manuel Barroso after pushing through parliament sweeping new cuts that have sparked violent protests. Germany meanwhile also wants the European Court of Justice to hammer states that break public finance obligations to EU partners, Foreign Minister Guido Westerwelle said on joining a marathon series of pre-summit meetings in Brussels. Demanding urgent changes to the EU's treaty, Westerwelle called for "a role for the European Court of Justice, to be called into action when (governments) continually break the rules" on public finances. To give "bite" to existing rules that are routinely ignored he said countries enjoying an EU rescue shield "must be prepared to give up a little bit of their sovereignty," suggesting "emergency interventions" by external auditors when they produce budgets. Germany wants the EU's Lisbon treaty re-written as its price for guaranteeing the lion's share of future eurozone bailouts, but Luxembourg's Jean Asselborn warned that ceding to domestic German politics would mean opening a "Pandora's Box" across the EU. On Monday, lawmakers in London will vote on whether to stage a referendum on Britain's continuing membership of the EU. While efforts in that direction are resisted by Prime Minister David Cameron, his finance minister George Osborne warned in Brussels that the crisis threatens the entire continent. "We've had enough of short-term measures, sticking plaster that just gets us through the next few weeks," he said, echoing broader concerns stretching from China to the United States. Eurozone ministers did achieve one small breakthrough late Friday by unblocking eight billion euros in EU-IMF aid for Greece from a first bailout package in 2010 that was quickly overtaken by events. But despite mounting international pressure to come up with an all-encompassing deal before the G20 grouping of the world's top economies meet in Cannes on November 3-4, the clock is running down quickly. EU President Herman Van Rompuy said Sunday's summit would prepare "decision making" on Wednesday.