Acknowledging that Europe’s banks still need billions of euros to cushion against a possible default by Greece, the leaders of Germany and France announced on Sunday that they would have a package of reforms by the time leaders of the Group of 20 nations meet in early November.

“We are determined to do everything necessary to ensure the recapitalization of Europe’s banks,” Chancellor Angela Merkel said in Berlin after meeting with President Nicolas Sarkozy of France.

But beyond promising closer coordination of economic policies for the euro zone, the two leaders declined to provide specifics on how the recapitalization would work, or how much money they would commit. The continued uncertainty could unnerve investors who hoped to see the governments take more decisive action.

The announcement came on the same day that the governments of France, Belgium and Luxembourg agreed to nationalize part of Dexia, Belgium’s biggest bank, infusing it with billions of euros in taxpayer money after it became the first casualty of the Greek sovereign debt crisis. Government officials had raced to prop up Dexia before global financial markets opened on Monday.