The work of reprocessing of all the 8,000 spent nuclear rods, a key step to increase its nuclear arsenal, had been completed by the end of August in Yongbyon, the official KCNA news agency of the Democratic People's Republic of Korea (DPRK) said on Tuesday.

"Noticeable successes have been made in turning the extracted weapons-grade plutonium for the purpose of bolstering up the DPRK's nuclear deterrent," the KCNA said, without elaborating.

The reprocessing was part of the measures to "restore the Yongbyon nuclear facilities to their original state" in response to the United Nations sanctions against it after the DPRK conducted a rocket launch and the second nuclear testing this spring, it said.

The report reiterated that the DPRK was compelled to "bolster up its deterrent for self-defense" in the face of "increasing nuclear threat and military provocation of the hostile forces."

The DPRK shut down Yongbyon in 2007 under a six-nation nuclear disarmament deal. In April, it quit the six-party talks and announced it was resuming the reprocessing of plutonium from spent fuel rods at the reactor there. Pyongyang has expressed willingness to return to the six-party talks but only if it first holds satisfactory talks with Washington.