The nation's large manufacturers are more confident about business conditions but have yet to recover their prequake optimism, the Bank of Japan's quarterly "tankan" sentiment index said Monday.

While midsize and small manufacturers did not share the sense of strong recovery, the sentiment index for big manufacturers — companies capitalized at ¥1 billion or more — climbed 11 points to 2 in September compared with minus 9 in June.

The improvement in sentiment was largely due to the recovery of the supply chain, which was reflected by a 65-point rebound by automakers to 13 from the June survey.