Foreign Ministry officials expressed puzzlement Wednesday over North Korean leader Kim Jong Il's failure to make a public appearance Tuesday to mark the hermit state's 60th anniversary.
Kim's absence from a military parade in Pyongyang prompted wide media speculation that he may be very ill.
"We are paying serious attention to the issue and gathering information," Foreign Ministry Press Secretary Kazuo Kodama told a news conference in Tokyo.
Meanwhile, a senior Foreign Ministry official in charge of North Korean issues described Kim's nonappearance as "something out of the ordinary," adding there was no apparent reason for the autocrat to skip the festivities if he were healthy.
While foreign media reports suggested Kim may have suffered a stroke in mid-August, the official said he could not verify any of the information with his overseas counterparts.
For his part, Kodama voiced concern that if Kim were in grave condition, North Korea may be unprepared for a leadership change.
Domestic disorder in North Korea will likely influence international talks to denuclearize the hermit state and hamper efforts by Tokyo and Pyongyang to restart the probe into the abduction of Japanese nationals, he said.
The official revealed that footage from Tuesday's celebration in Pyongyang is being closely examined for any signs of a shift in power.
"I remember that the death of Kim Il Sung (Kim's father and former leader of North Korea) was revealed a day after his death," Kodama said.
But he speculated that even if Kim Jong Il were dead, the news would not be made public until a successor emerged.