Business sentiment among the nation's corporations improved over the past three months, underscoring a recent recovery trend, according to the Bank of Japan's "tankan" business sentiment survey for June.

The June results of the central bank's quarterly survey, released Tuesday, are expected to be a strong factor in the BOJ's decision on whether to end its 17-month-old "zero-interest-rate" policy.

Tuesday's results show the diffusion index -- the percentage of firms that feel business is favorable minus those that feel the opposite -- rose for firms in all four categories: large and small manufacturers and nonmanufacturers.