* Big manuf sentiment +6 vs previous +12
* Big non-manuf sentiment +22 vs previous +25
* Big firms' FY2016 capex seen down 0.9 pct
* Adds pressure on PM Abe, Bank of Japan for more stimulus (Adds analyst quote, details)
By Leika Kihara and Tetsushi Kajimoto
TOKYO, April 1 (Reuters) - Business sentiment among Japan's big manufacturers deteriorated to the lowest in nearly three years and is expected to worsen in the coming quarter, a closely watched central bank survey showed on Friday, heightening pressure on Prime Minister Shinzo Abe and the Bank of Japan to do more to shore up the ailing economy.
Big firms also plan to cut capital expenditure plans in the current fiscal year, underscoring the challenges the BOJ faces in aggressively printing money to nudge risk-shy companies into boosting spending.
To keep the economy afloat, Abe may have to delay yet again a sales tax hike scheduled for next year.
The weak reading will also keep the BOJ under pressure to loosen monetary policy further when it reviews its quarterly forecasts later this month, some analysts say.
"This data confirmed the very cautious stance of Japanese firms reflecting the market volatility since January. There's no signs of corporate sentiment bottoming in coming months," said Mari Iwashita, chief market economist at SMBC Friend Securities.
"There's more than a 50 percent chance the BOJ will consider easing policy further this month."
The headline index gauging big manufacturers' sentiment stood at plus 6 in March, half the level seen three months ago and worse than a median market forecast of plus 8, the survey showed.
It was the lowest reading since June 2013, as exporters felt the pinch from sluggish emerging market demand and yen rises that erode their competitive advantage overseas.
Big non-manufacturers' sentiment dropped to plus 22 from plus 25 three months ago, deteriorating for the first time in six quarters, as spending by overseas visitors moderated.
Sentiment soured for manufacturers and non-manufacturers big and small for the first time since June 2014, when Japan was reeling from the blow of a sales tax hike in April of that year.
Both big manufacturers and non-manufacturers expect sentiment to worsen in the coming three months, underscoring companies' concern over the murky global economic outlook.
"The slowdown in emerging economies, particularly that of China, has affected business sentiment. The impact was big for big manufacturers with direct exposure to global economic conditions," a BOJ official told reporters in a briefing.
The yen's rise is also expected to hurt profits.