Business sentiment among large Japanese firms deteriorated in the October-December quarter from the previous three months amid worries over a strong yen and deflation, a government survey showed Thursday.

The index of business conditions at companies capitalized at ¥1 billion or more came to minus 1.9, compared with plus 0.3 in the three months through September, when it returned to positive territory for the first time in seven quarters, said the survey conducted by the Cabinet Office and the Finance Ministry.

The sentiment substantially weakened from the previous survey, in which the industrywide index was projected to post plus 4.9 in the last quarter of 2009.