BEIJING, June 1 (Reuters) - Growth in China's services industry cooled in May, an official survey showed on Monday, suggesting the country's worst economic downturn in at least six years may be deepening.

The non-manufacturing Purchasing Managers' Index (PMI) edged down to 53.2, from April's 53.4, the National Bureau of Statistics said on its website.

A reading above 50 points indicates growth on a monthly basis, while one below that points to contraction.

Growth in China's services companies has been more resilient than at its ailing factories, but the sector has succumbed to the broader economic cooldown in recent months.

Many analysts expect growth in China's economy to cool to 7 percent this year compared to 2014, the weakest rate of expansion that the country has seen in a quarter of a century.

(Reporting by Koh Gui Qing; Editing by Kim Coghill)