Pyongyang has again demanded that Seoul fully disclose its past nuclear activities. Otherwise, it says, no progress can be made in the six-way nuclear talks.

In an interview with the North's official KCNA News Agency, a Northern Foreign Ministry spokesman said suspicions surrounding South Korea's "secret nuclear experiments" are continuously rising.

The spokesman criticized the United States for what the North claims are "double standards" on nuclear issues on the Korean Peninsula, saying that such standards have placed a permanent stumbling block in the path of seeking a peaceful resolution to Pyongyang's nuclear impasse.