"Led by the United States, prospects for a recovery are firming in the advanced economies," Koehler said at an economics conference in Vienna.

"But we know that risks remain. Chief among these risks is the excessive dependence of the world economy on growth in the US and the resulting global current account imbalances," he warned.

Koehler emphasized the need for cooperation among the four main economic pillars: the US, Japan, Europe and emerging economies.

"Resolving the imbalances in an orderly manner must be the primary objective of international economic policy," he said, speaking on the opening day of an annual conference on central European economies organized by the Austrian central bank.

He said it was critical that the US restore medium-term fiscal balance to support the economy.

The 12-state euro zone is showing more tentative signs of recovery, he said.

"But there are increasing signs of returning confidence and it is encouraging that several euro area economies have initiated long-overdue structural reforms."

In Japan, recent data indicates a firming of the short-term economic outlook, he said, stressing the need to continue to pursue structural reforms.