BEIJING // South Korea accused North Korea yesterday of operating its uranium-enrichment programme to develop nuclear weapons and said it does not believe Pyongyang's denials.
The comments from the South Korean foreign minister came as Washington also said North Korea must show it was "serious" before six-party talks could resume.
After the existence of a North Korean uranium-enrichment facility was revealed late last year, the usually secretive regime insisted the complex was part of a peaceful energy programme.
Yet in an interview with the South Korean government-affiliated Yonhap news agency published yesterday, the South Korean foreign minister, Kim Sung-hwan, made the strongest comments yet from Seoul suggesting it did not believe Pyongyang.
"It is difficult to see that what North Korea has done so far is to address its energy problem," Mr Kim said. "As the north has made nuclear weapons with plutonium, we believe this is part of such an attempt."
While the South Korean president, Lee Myung-bak, recently indicated the six-party talks could resume this year, Mr Kim said before this could happen, North Korea must admit its part in the sinking in March of the South Korean naval vessel Cheonan, which claimed 46 lives.
Additionally, he said Pyongyang must promise there would be no further attacks such as the bombardment in November of Yeonpyeong island, in which four died. "There should be a firm pledge that such provocations won't be repeated and we also have to first make sure [North Korea] is serious about denuclearisation," Mr Kim said.
Seoul and Washington are concerned North Korea is looking to resume talks to secure economic concessions and aid, without taking steps to rein in its nuclear programme.
"They would like to make sure, if they go back to the negotiating table, there will be concrete results," said Joseph Cheng, a professor of political science at City University of Hong Kong.
In Tokyo, the US defence secretary, Robert Gates, said the north must demonstrate its good faith if the talks are to reconvene.
"There must be concrete evidence that they are fairly serious about negotiations," he said.
During a visit to Beijing this week, while warning North Korea was becoming a growing threat to the United States itself, Mr Gates said Pyongyang must halt any future nuclear or missile tests as a sign of its willingness to dismantle its nuclear programme.
Six-party talks, involving both Koreas, China, Russia, the US and Japan, have been stalled since April 2009 when Pyongyang pulled out. Both North Korea and its main ally, China, have called for the unconditional resumption of the discussions.
The impoverished North Korea has this week also called for talks about renewing South Korean involvement in an industrial zone and on resuming a lucrative tour programme to a resort in North Korea. Mr Kim said the two sides could "easily" make progress on these issues if North Korea demonstrated its intent over the nuclear issue.
The visit by the Chinese president, Hu Jintao, to Washington next week for a summit with his US counterpart, Barack Obama, may see the parties move closer to a resumption of the six-party talks, Mr Cheng suggested.
China's role in helping to scale back tensions on the Korean peninsula was recently acknowledged by Mr Gates, who arrives in Seoul today for talks.