Big Japanese manufacturers' business confidence improved for a fifth straight quarter in the three months to December to hit a 11-year high, a central bank survey showed, a sign the economy is gathering momentum from robust exports and booming corporate profits.

The data may help the Bank of Japan (BOJ) make the case that strengthening economic recovery will prompt firms to raise wages and allow it to edge away from crisis-mode stimulus, even before inflation hits the central bank's elusive 2 percent target.

The headline index for big manufacturers' sentiment stood at plus 25 in December, the BOJ's closely watched "tankan" survey showed on Friday, up from plus 22 in September and slightly higher than a median market forecast for plus 24. It matched a high marked in December 2006.

An index measuring big non-manufacturers' sentiment was unchanged from September at plus 23, matching a median market forecast. Big manufacturers and non-manufacturers expected business conditions would worsen in the next three months, the poll found.

Big firms expect to increase capital expenditure for the current fiscal year to March 2018 by 7.4 percent, compared with a median market forecast for a 7.5 percent gain, it showed.