The agreement was reached during an all-night negotiating session of finance ministers that ended early Thursday after France and Germany made significant compromises. Under the agreement, 100 to 200 large banks in the euro zone will fall under the direct supervision of the European Central Bank.
A round of talks a week earlier broke up because of French and German discord over how many banks in the currency union should be covered by the new system.
In a concession to Germany, the finance ministers agreed that thousands of smaller banks would be primarily overseen by national regulators. But to satisfy the French, who wanted all euro zone banks to be held accountable, the central bank will be able to take over supervision of any bank in the region at any time.
The agreement by the finance ministers, which still requires the approval of the European Parliament and some national parliaments including the German Bundestag, made it possible for European Union leaders arriving here later Thursday to gather in a spirit of unity.
“It’s a good day for Europe,” said President François Hollande of France. “The crisis came from the banks, and mechanisms have been put in place that will mean nothing is as it was before.”
Angela Merkel, the German chancellor, said the agreement was “a big step toward more trust and confidence in the euro zone.” The summit meeting could now focus on “strengthening economic coordination” and “set out a road map for the coming months,” she added.
In another measure to shore up the euro, the finance ministers approved the release of nearly 50 billion euros, or $65 billion, in further aid to Greece, including long-delayed payments, support that is crucial for the government to avoid defaulting on its debts.
“Today is not only a new day for Greece, it is indeed a new day for Europe,” Antonis Samaras, the Greek prime minister, said ahead of the summit meeting.
But threatening to spoil the upbeat atmosphere were questions over the future leadership of Italy, where the economy is contracting, debt levels are rising and Silvio Berlusconi, the former prime minister, has threatened to try to reclaim the office in an election next year.
It remained unclear on Thursday whether Mr. Berlusconi would run and, if that were to happen, whether he would campaign on promises to reverse reforms put in place by Mario Monti, the current prime minister. Even so, the re-emergence of Mr. Berlusconi — who attended a summit meeting of center-right parties in Brussels on Thursday — could destabilize markets and even rekindle the financial crisis.
The bank supervision plan was first discussed in June and wrapped up in a matter of months — record time by the glacial standards of European Union rule-making. The agreement should serve as a springboard for leaders to weigh further steps toward economic integration during their meeting.
Such measures could include a unified system, and perhaps shared euro area resources, to ensure failing banks are closed in an orderly fashion. This could be followed, in time, by actions intended to reinforce economic and monetary union, including, possibly, the creation of a shared fund that could be used to shore up the economies of vulnerable members of the euro zone.
Mario Draghi, the president of the European Central Bank, said the agreement on banking supervision was “an important step towards a stable economic and monetary union, and toward further European integration.” But he noted that governments and the European Commission still had to work on the details of the supervision mechanism.
The new system should be fully operational by March 2014, but the ministers left the door open for the central bank to push that date back if it would “not be ready for exercising in full its tasks.”
A series of compromises was needed for finance ministers to reach agreement on banking supervision.
Initially, France and the European Commission had asked that all 6,000 banks in the euro area be closely regulated by the central bank. But in a concession, France agreed that only banks holding more than 30 billion euros in assets, or assets greater than 20 percent of their country’s gross domestic product, would be directly regulated by the central bank.
Germany, seeking to make the central bank’s job more manageable and facing pressure from a powerful domestic banking lobby trying to shield many small savings banks from closer scrutiny, sought a reduced portfolio for the bank. But Germany agreed to let the central bank, at its discretion, step in and take over supervision of any euro zone bank.
The Germans and Swedes also had concerns that the central bank could be tempted to alter its decisions on monetary policy to make its supervisory job easier. As a compromise, member states are to be given greater scope than originally foreseen to challenge central bank decisions.
Britain, which is not a member of the euro zone, sought assurances that the new banking supervisor would not have influence over banks operating in the City of London. Britain agreed to a formula that should allow it and other European Union members outside the euro zone to counteract most — but probably not all — rule-making by the central bank. These countries will also be able to challenge decisions pertaining to cross-border banking.
The supervisor is a prerequisite for a new European bailout fund, the European Stability Mechanism, to provide aid directly to the troubled banks of countries including Spain and Ireland. Such aid would allow those governments to avoid weighing down their national balance sheets with yet more debt. Those countries, along with France, successfully lobbied for direct recapitalization of banks to be mentioned in the agreement.
But in a concession to Germany, which is wary about spending more money on bailouts ahead of national elections in late 2013, and to assuage similar concerns by the Dutch and Finns, the agreement underlined the need for unanimity among states contributing to the bailout fund before any such measures can go ahead.
Niki Kitsantonis contributed reporting from Athens.
