Business confidence among the nation's largest manufacturers remained upbeat in September despite the global financial turmoil triggered by U.S. housing woes, the Bank of Japan's quarterly survey of business confidence, or "tankan," showed Monday.

The business sentiment index for major manufacturers stood at 23, slightly above the market's forecast of 21. It stayed at the same level from the previous survey's reading in June, indicating that business remains generally upbeat.

Meanwhile, business sentiment among major nonmanufacturers and small- and medium-size companies worsened from three months earlier.