WASHINGTON (Kyodo) Dominique Strauss-Kahn, managing director of the International Monetary Fund, said uncertainty is prevailing in the global economy, with the impact on the Japanese economy of the March 11 earthquake and nuclear crisis remaining unclear.

A "large part of the Japanese economy has been destroyed. . . . We're still hesitating, depending on what may happen on the nuclear side of course," Strauss-Kahn said in a speech Monday at George Washington University in Washington.

"Great uncertainty is prevailing, with a number of black swans swimming in the global economic lake," he said, adding the first thing that comes to mind is the disaster in Japan.

While the world has been impressed by the resilience of the Japanese people amid the tragedy, Japan "may need some special efforts" to rebuild and recover from the disaster, Strauss-Kahn said.

His remarks came ahead of talks among finance ministers and central bank governors from the Group of 20 as well as a series of meetings of the IMF and the World Bank next week.

The IMF chief said global economic growth remains uneven, calling for greater international cooperation to address economic challenges.