THE HAGUE (REUTERS) - US President Barack Obama and Japanese Prime Minister Shinzo Abe said on Monday that Japan would turn over a stockpile of highly enriched uranium (HEU) and separated plutonium to the United States to be downgraded and disposed of.

"This effort involves the elimination of hundreds of kilograms of nuclear material, furthering our mutual goal of minimising stocks of HEU and separated plutonium worldwide, which will help prevent unauthorised actors, criminals, or terrorists from acquiring such materials," the leaders said in a joint statement released by the White House.

"This material, once securely transported to the United States, will be sent to a secure facility and fully converted into less sensitive forms."

The plutonium, they said, would be prepared for "final disposition."

The announcement was made as world leaders convened in the Netherlands for a nuclear summit.