European banks should be supervised by a cross-border authority providing bloc-wide deposit cover and a rescue pot funded by taxes on financial institutions, EU Commission chief Jose Manuel Barroso said on Tuesday.

The president of the European Union's executive arm told London-based Financial Times newspaper that the ambitious plan could be realised by next year without the need for existing treaties to be changed.

"There is now a much clearer awareness among European member states about the need to go further in terms of integration, especially in the euro area. This is one lesson of the crisis," he told the business daily.

His views were echoed by French Finance Minister Pierre Moscovici, who said the aid package of up to 100 billion euros for Spain's banks was just the first step towards a banking union.

Moscovici said events in the coming weeks, including the legislative elections in Greece and France next weekend and a summit of European leaders at the end of June, would prove decisive for the future of Europe.

"What we did for Spain was a convincing step forward but we must go further still," the minister told Europe 1 radio.