"The conditions are that North Korea accept inspections by the International Atomic Energy Agency and close its nuclear test facility," Aso told reporters. US financial sanctions "have nothing to do with the six-party talks. That is a separate issue," Aso said.

North Korea in 2002 expelled inspectors from the UN atomic watchdog and restarted its Yongbyon facility, which could produce weapons-grade plutonium, after the United States accused Pyongyang of secret nuclear activity. North Korea last month returned to six-nation talks -- involving China, Japan, the two Koreas, Russia and the United States -- after carrying out its first nuclear test.

US negotiator Christopher Hill, who was in Seoul Friday after meeting his North Korean counterpart in Berlin, said he expected six-way negotiations to resume before mid-February. Hill will visit Tokyo on Saturday for talks with his Japanese counterpart Kenichiro Sasae. Aso said he was unsure when the talks would start. "We don't have a clear view on when North Korea will come to participate in the talks. We have no idea when the next talks will be held."

Prime Minister Shinzo Abe said that the parties concerned should make six-way talks "fruitful" if they are resumed. "I have given instructions that close consultations with the United States and other countries must be made in an effort to make a new round fruitful with North Korea taking concrete action toward dismantling its nuclear arms," Abe told reporters at his office. Japan has tense relations with North Korea and Abe has pursued a hard line against the communist state.