Spanish officials on Saturday denied that their country was in the same position as Greece, Portugal and Ireland, which have all received bailouts that demanded they slash spending. And on Sunday, Mr Rajoy rejected suggestions that Spain had been pushed to request help ahead of new Greek elections on June 17 that could precipitate Greece’s withdrawal from European monetary union.

“Nobody pressured me, I was the one who pressured to get credit,” Mr Rajoy said.

Luis de Guindos, the Spanish economy minister, said at a news conference Saturday in Madrid that the assistance “allows us to have an ample safety margin” and “will return trust and confidence to the euro project.”

The deal to shore up Spain’s banks is only the latest in a marathon crisis that has seen one stopgap solution after another over the last three years. The 11th-hour fixes have always given way to new speculation about the long-term solidity of the currency union, and European leaders remain deeply divided about the way to carry out a more lasting solution. Ahead of a summit meeting this month, members of the euro zone are debating a variety of fixes related to forming a tighter political and fiscal union.

The amount of the financing package is expected to be completed after two consulting firms publish their audit reports on Spanish banks on June 21.

The maximum figure of $125 billion was intended to cover the “estimated capital requirements with an additional safety margin,” according to the statement issued by euro zone finance ministers. The statement also said that the euro group “supports the efforts of the Spanish authorities to resolutely address the restructuring of its financial sector.”

Christine Lagarde, the managing director of the I.M.F., said the scale of the proposed financing “gives assurance that the financing needs of Spain’s banking system will be fully met.” And the United States Treasury secretary, Timothy F. Geithner, called the support European partners were showing Spain “important for the health of Spain’s economy.” He said that Spain’s request for aid and Europe’s agreement were “concrete steps on the path to financial union, which is vital to the resilience of the euro area.”