The Obama administration on Tuesday accused the Democratic People's Republic of Korea (DPRK) of violating UN Security Council resolutions to produce material useable in nuclear weapons, urging the country back to the six-party process.

"It certainly runs counter to the commitment that they made in 2005, and it violates UN Security Council resolutions," State Department spokesman Ian Kelly told reporters.

"What we're focused on with North Korea is getting to the point where we can re-launch the six-party talks, which will get us to our ultimate goal, which is the denuclearization of the Korean Peninsula," said the spokesman.

Earlier on Tuesday, the official KCNA news agency of DPRK said that 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 reprocessing was part of the efforts to "restore the Yongbyon nuclear facilities to their original state" in response to the UN sanctions against it after the DPRK conducted a rocket launch and the second nuclear testing this spring, the KCNA said.

The DPRK shut down the Yongbyon nuclear facility 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.