High-level talks between Japan and North Korea due to take place this weekend have been postponed.
According to a Japanese government minister, the North Koreans called off the meeting saying they were not ready.
The official focus was financial aid for Korean survivors of the 1945 atomic bomb explosions in Japan.
But the issue of Japanese nationals alleged to have been abducted by North Korea more than 20 years ago was also expected to be raised by Tokyo.
Japan believes at least 11 people kidnapped by North Korea
Used to teach North Korean spies Japanese language and culture
Spies then entered South Korea posing as Japanese tourists
The talks would have been the first ministerial-level meeting between the two countries since July 2000.
Japanese Health Minister Chikara Sakaguchi, who was supposed to fly to Singapore on Saturday for the meeting with his North Korean counterpart, expressed irritation about Pyongyang's decision.
"I think their attitude is very insincere... Even if they say they want to rearrange the talks, I am not sure I would want to go ahead", he was quoted as saying.
Japan was told North Korea had not completed preparations for the talks
He suggested North Korea might have backed off after reports that he would he press them about the issue of the "kidnapped" Japanese.
"I get the feeling they may have wanted to meet very privately and were put off by the publicity", he said.
There has been no word from the North Koreans.
Japan believes at least 11 of its nationals were kidnapped by North Korea in the 1970s and 80s to train as spies or teach agents Japanese language and culture.
Pyongyang has repeatedly denied involvement.
The issue has hampered negotiations between the two countries on establishing formal diplomatic relations.
South's diplomatic push
The cancellation of the Singapore talks comes amid indications North Korea may be inching back towards dialogue with South Korea and the US, after several months of silence.
South Korea is to send an envoy to North Korea next week to try and restart suspended talks after a four-month break in contacts.
The south hopes the visit will help to reduce tensions on the divided peninsula ahead of the football World Cup, which it is co-hosting.
North Korea is also expected to be pressed to resume talks with the South by Indonesian President Megawati Sukarnoputri who is currently in Pyongyang.
She met North Korean leader Kin Jong-il on Saturday, though no details of their talks were released.