North Korea has declared that it used two kilograms of plutonium for testing in October 2006.

A diplomatic source said the declared total of 37-point-nine kilograms accounted for the extracted amount in addition to those available in fuel rods at the North's nuclear facilities, which were under denuclearization.

Pyongyang said it had extracted 30-point-nine kilograms of plutonium through reprocessing.

North Korea submitted its long-delayed declaration to China, the chair country of the six-party talks, last week.