Japanese Prime Minister Yoshihiko Noda instructed ministers at a special security meeting to prepare for any unexpected circumstances, including financial issues or border affairs, following news of the death of North Korean leader Kim Jong-il, the top government spokesman said on Monday.
Chief Cabinet Secretary Osamu Fujimura also told a news conference that Japan would work closely with the United States, South Korea and China in seeking further information.
He said the ministers had reached no conclusion on whether to raise the level of alert for Japan's military, but that the matter might be raised in subsequent meetings.
Kim died of a heart attack on Saturday while on a train trip, state media reported on Monday, sparking immediate concern over who is in control of the reclusive state and its nuclear programme.
(Reporting by Rie Ishiguro and Leika Kihara; Editing by Michael Watson)