WASHINGTON (Yonhap News) ― South Korea cannot agree to resume six-party talks on North Korea’s nuclear programs unless the illicit nature of Pyongyang’s uranium enrichment is clearly defined first, a senior official said Friday.

“We have to get the (U.N.) Security Council to define the nature of this matter and take corresponding steps,” the official told South Korean reporters in Washington. “The point is that the international community should define the North’s UEP (uranium enrichment program) issue as a violation of Security Council resolutions that should be stopped.”

North Korea revealed in November that it was running a uranium enrichment facility, adding to international concerns about its nuclear capabilities. Uranium, if highly enriched, can be used to make weapons, providing Pyongyang with a second way of building atomic bombs after its existing plutonium-based program.

Pyongyang has said the purpose of the facility is to produce fuel for a power-generating nuclear reactor and that the country has the right to peaceful use of nuclear energy. But few believe the claim by a regime that has pursued nuclear ambitions for decades and conducted nuclear tests twice.

South Korea and the U.S. have called for a tough response to the uranium program, including taking the matter to the Security Council. But China, the North’s last remaining major ally with veto powers at the council, has been the biggest obstacle to the move.

Earlier last week, China blocked the Security Council from adopting an experts’ report denouncing the uranium program. Beijing is concerned that such a move could aggravate tensions and insists that the issue should be discussed at six-party talks.

“Uranium enrichment is another route to nuclear weapons development, along with plutonium. Anybody would know the intentions behind uranium enrichment by North Korea, which conducted nuclear tests twice,” the senior South Korean official said. “It is not the right approach to leave this issue as it is and go discuss it at six-party talks.”

Unless the program’s nature is defined first, six-party talks cannot make any substantial progress, even if reconvened, because the North is sure to claim at the talks that the program is for peaceful purposes, the official said.

The six-party talks, which bring together the two Koreas, China, Japan, Russia and the U.S., have been stalled since December 2008 due to North Korea’s boycott and tensions over its provocations.