Report: No Proof N. Korea Is Producing Plutonium

File: The cooling tower of North Korea's Yongbyon nuclear complex, a plutonium-producing reactor, was demolished on June 27, 2008. (Reuters)

SEOUL, South Korea – U.S. and South Korean authorities have found no concrete evidence yet that North Korea is reprocessing spent nuclear fuel rods to harvest weapons-grade plutonium, a news report said Wednesday.

North Korea said last month it had begun the reprocessing work at its once-mothballed Yongbyon nuclear complex — one of a series of steps the communist nation has taken in protest over international criticism of its April 5 rocket launch.

Pyongyang has also quit international nuclear talks, kicked out all international nuclear monitors and threatened to conduct its second nuclear atomic blast and a long-range missile test.

The North conducted its first-ever nuclear test in 2006 and is believed to have enough plutonium for at least half a dozen atomic bombs.

U.S. and South Korean authorities have been using spy satellites and krypton gas sensors to determine whether the reprocessing work has started, but no concrete proof has been found, Seoul's Yonhap news agency reported Wednesday, citing an unnamed official.

A kind of krypton gas is released when spent fuel rods are reprocessed, and its detection is considered evidence that the reprocessing work is under way. Sensors are deployed near the border with the North to detect the inert gas, Yonhap said.

Seoul's Foreign Ministry spokesman Moon Tae-young said he does not comment on intelligence matters.

Yonhap said satellite images have shown trucks moving back and forth from the North's reprocessing plant, but it is difficult to determine from the images whether the reprocessing has started.

The chief U.S. negotiator for North Korea, Stephen Bosworth, has returned to Washington after trips to China, South Korea and Japan for talks on how to break the deadlock. He said during the trip that Washington is ready for direct talks with Pyongyang.

There is a "common desire" for a return to the six-party process, Interfax news agency quoted the Russian envoy to the stalled nuclear talks, Grigory Logvinov, as saying after he met with U.S. envoy Sung Kim.

North Korea has said talks with Washington are useless because the administration of President Barack Obama is hostile toward it.