NEW YORK - Moody's Investors Service said Thursday that it has reaffirmed all its ratings assigned to the 16 major Japanese banks and that their rating outlooks remain stable.

The action came a day after the rating agency Fitch put Japan's major banks on watch for downgrade, a move that prompted concern about U.S. banking companies' exposure to the sector.

Moody's said it already had assigned a majority of Japanese banks the lowest ratings in its financial strength rating scale and that financial difficulties such as low capitalization have been long identified as generic problems for Japanese banks as reflected in its ratings.

However, Moody's also stressed that its ratings on the major banks' deposits were in investment grade ranges, which it said indicated a "strong expectation" that Japanese government support would be available, if necessary, to the institutions.

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