Japan has information that North Korea may be preparing for a nuclear test, a Defense Agency official said Friday, less than a week after Pyongyang is believed to have tested a short-range missile off its eastern coast. The official, who spoke on condition of anonymity, refused to specify the information or its source. An official at the Foreign Ministry said Japan was exchanging information on North Korea with "concerned countries," but did not confirm that there were signs of an imminent test.The New York Times on Friday reported that the White House and Pentagon officials were examining satellite photographs that suggest North Korea is making rapid preparations for a nuclear test. The report, which cited unidentified American and foreign officials, also said that the U.S. had extensively briefed Japan and South Korea on the preparations. Japanese officials refused to confirm they had been briefed on the possible test by the Americans. Japan, which is in range of Pyongyang's missiles, has been working with the United States, South Korea and China to draw North Korea back to six-party talks on its nuclear weapons programs. Pyongyang is boycotting the talks, and Japanese Foreign Minister Nobutaka Machimura told reporters on Friday that Tokyo could push to bring the case to the U.N. Security Council if there is no progress in the negotiations.