TOKYO, April 1 (Reuters) - Confidence at big Japanese manufacturers worsened in the three months to March and is seen falling further ahead, a closely watched central bank survey showed on Friday.

The headline index for big manufacturers' sentiment stood at plus 6 in March, down from plus 12 seen three months ago, the Bank of Japan's quarterly "tankan" survey showed.

That compared with the median estimate of plus 8 in a Reuters poll of economists.

Big firms plan to cut capital expenditures by 0.9 percent in the fiscal year that started in April, compared with economists' median estimate of a 0.7 percent decline.

The tankan's sentiment indexes are derived by subtracting the number of respondents who say conditions are poor from those who say they are good. A positive reading means optimists outnumber pessimists.

To view the table on the survey, go to the BOJ website:

http://www.boj.or.jp/en/statistics/tk/yoshi/tk1603.htm (Reporting by Leika Kihara and Tetsushi Kajimoto; Editing by Sam Holmes and Chris Gallagher)