U.S. Secretary of Energy Spencer Abraham told reporters the United States is concerned that nuclear materials could fall into the hands of terrorists or, "a madman whose ambition is to destroy a world capital."

"One area that clearly has arisen as an area of priority is the need for us, in affect, to undertake a global cleanout of those radiological materials that remain in the world that either are not sufficiently secured or are of such highly dangerous composition that they require further attention," he said. "Today I announced a Global Threat Reduction Initiative, which my department will be heading up on behalf of President Bush and the United States government."

The United States is putting up $450 million to start the program in partnership with Russia and the IAEA.

The plan is to remove, store or convert dangerous nuclear materials from hundreds of research reactors worldwide. It calls for the repatriation of unused highly enriched uranium of Russian origin by the end of next year and all spent nuclear fuel by the end of the decade.

It is estimated that around 200 research reactors are coming to the end of their life span.

The head of the IAEA, Mohamed ElBaradei, told the news conference that dangerous materials had to be controlled because of the threat posed by the global nuclear black market.