European leaders' blueprint for a closer fiscal union to save their single currency left the onus on central bankers to address investor concerns that Italy and Spain would succumb to the two-year-old financial crisis.

While European Central Bank President Mario Draghi hailed the accord struck at all-night talks in Brussels, investors urged him to expand his crisis-fighting arsenal to ensure debt-addled nations can pay their bills. Italian bonds fell today even as the ECB was said to be buying them in the market.

"The leaders have now defined the end point they want to reach in terms of fiscal governance, but it's a long way to go there," Thomas Mayer, London-based chief economist at Deutsche Bank AG, told Bloomberg Television. "We'll probably see more near-term tension and that will probably then trigger a more hands-on intervention by the ECB."