By Leika Kihara and Tetsushi Kajimoto
TOKYO (Reuters) - Business confidence among Japan's big manufacturers worsened in the September quarter to hit the lowest level in nearly a year, a closely watched central bank survey showed, as firms felt the pinch from rising raw material costs and a string of natural disasters that disrupted production.
The survey showed little indication underlying sentiment had been hit by escalating global trade frictions, but the spectre of a fully-fledged trade war weighed on companies' business outlook.
The survey casts doubt on the BOJ's projection that a solid economic expansion will help accelerate inflation to its elusive 2 percent target, although there were some signs that companies were gradually passing costs to their customers.
"Sentiment is levelling off due to slowing exports and weakening factory output amid worries of a global trade war," said Takeshi Minami, chief economist at Norinchukin Research Institute.
"Still, the level of sentiment index is high. I don't think it will keep deteriorating either, given improving profits and rising prices."
The headline index for big manufacturers' confidence fell to plus 19 in September from plus 21 three months ago, the BOJ's tankan survey showed on Monday, deteriorating for three straight quarters. It compared with a median market forecast for plus 22.
The index for non-manufacturers fell to plus 22 from plus 24 in the June survey, worsening for the first time in eight quarters. The reading compared with a market forecast of plus 22.
Both big manufacturers and non-manufacturers expect business conditions to remain unchanged three months ahead, the survey showed.
Big companies plan to increase capital expenditure by 13.4 percent in the current fiscal year ending in March 2019, compared with 13.6 percent in the previous tankan survey.
Japan's economy rebounded in the second quarter from a contraction in the first three months of this year thanks to robust business spending.
But escalating trade frictions and a series of natural disasters that disrupted supply chains cloud the outlook for the export-reliant economy.
(Additional reporting by Stanley White; Editing by Eric Meijer)