China's service sector growth slightly softened in August from a 15-month high in July but maintained strong growth and recovery trend following a recent wave of COVID-19 cases, a private survey showed on Monday.

The Caixin general service purchasing managers' index (PMI) edged down 0.5 percentage point to 55 in August, in line with the movements in the official PMI gauge released last week. The 50-point mark on the index separates growth from contraction.

The survey, compiled by S&P Global, found that growing customer demand and rising intakes of new work boosted businesses in August as pandemic restrictions continues to recede.

It added that domestic demand outperformed export sales, pushing up the total new orders.

Optimism among Chinese service providers elevated to a multi-month high, which supports future business expansion and new product launches, the survey showed.

"The future activity expectations measure came in at the highest in nine months, with companies expressing confidence about further economic recovery from the pandemic," wrote Wang Zhe, senior economist at Caixin Insight Group, commenting on the data.

The Caixin composite PMI, which includes both manufacturing and services activity, slipped to 53 in August from 54 in July, mainly weighed down by a record heat wave and resurgence of COVID-19 cases in Chinese cities.

"The impact of the extreme weather was more significant than that of the outbreaks," wrote Wang.

He added that the heat wave-induced power shortages restrained factory activities but caused little damage to the service sector.

China is due to unveil more detailed policies in the coming days to boost demand and stabilize the foundation of economic recovery, according to a State Council executive meeting chaired by Premier Li Keqiang last week.

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