ECB President Mario Draghi endorsed the "tangible results", which sent the euro nearly 2 percent higher and sharply cut Spanish and Italian bond yields. European shares rose, led by banking stocks buoyed by the prospect of moves to backstop the financial system.

"I am actually quite pleased with the outcome of the European Council. It showed the long-term commitment to the euro by all member states of the euro area," Draghi told reporters.

Market participants welcomed the outcome as a substantial step to restore confidence in the 17-nation euro zone, which was saluted by a more durable rally than previous summit outcomes.

"It's inching closer to a banking union, and the closer we get to a banking union would put (the EU) well on the road to a fiscal union," said Art Hogan, managing director of Lazard Capital Markets in New York.

Most economists polled by Reuters expect the ECB to cut borrowing costs at its July 5 meeting, which takes place against a darkening economic backdrop. But internal resistance to the central bank reviving its bond-buying program remains high.