The seasonally adjusted Nikkei India Composite PMI Output Index -- that maps both the manufacturing and services sectors -- fell from 52.6 in August to 51.5 in September, highlighting the weakest rate of expansion in the current period of growth.
Meanwhile, the Nikkei Business Activity Index, also fell from 51.8 in August to 51.3 in September as "tough economic conditions weighed on growth", the survey showed.
A reading below 50 means contraction in the sector.
Meanwhile, according to an earlier Nikkei survey, factory output for September had dropped to a seven-month low.
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"Lower commodity prices coupled with falling petrol costs resulted in an overall drop in average input prices. On the back of this, businesses lowered their tariffs," Lima added.
"Looking ahead, service providers expect further setbacks, as highlighted by the Future Output Index sliding to its lowest mark in the history of the series," Lima added.
On Reserve Bank's policy rates, Lima said the bank "continued its attempt to shift India's growth momentum into a higher gear."
Reserve Bank Governor Raghuram Rajan, on September 29, effected a more-than-expected interest rate cut of half a per cent to boost the economy.
Moreover, the RBI also lowered its economic growth forecast for the current fiscal to 7.4 per cent from its previous projection of 7.6 per cent.