MOSCOW, June 8. /TASS/. Reports on the resumption of weapons-grade plutonium production in North Korea raise concerns, Russian presidential spokesman Dmitry Peskov said on Wednesday.

"Indeed, this continues to trigger concern," he told reporters. "All known countries that favor the denuclearization of the Korean Peninsula are particularly concerned and continue meticulous work with the North Korean side," Peskov added.

Reuters earlier reported citing its own sources in the US Department of State that the North Korean authorities had resumed plutonium production for use in munitions.

The situation on the Korean Peninsula deteriorated after North Korea conducted a nuclear test on January 6 and launched an artificial Earth satellite into space on January 7 in violation of UN Security Council decisions. In response, the Security Council unanimously passed a resolution on tightening sanctions against North Korea.