South Korea says Pyongyang's recent declaration it has harvested more material for producing nuclear weapons is a negotiating tactic.
The North Korean government said Wednesday it had extracted 8,000 spent fuel rods from a nuclear reactor.
South Korean Vice Unification Minister Rhee Bong-jo told reporters in Seoul Thursday, Pyongyang's latest move was likely intended to gain an advantage in any future talks on its nuclear program.
He said North Korea should immediately return to six-party negotiations instead of taking what he called "unhelpful measures." It has been almost a year since the last round of talks.
The U.S. envoy on the North Korean Nuclear issue, Christopher Hill, is scheduled to arrive in Seoul Friday for meetings with South Korean officials on ways to end the impasse over the talks.
Some information for this report provided by AP, AFP and Reuters.