China's services sector was more active than expected in May, with a private survey pointing to the fastest pace of expansion in four months thanks to a surge in new orders.

The Caixin/Markit services purchasing managers' index (PMI) rose to 52.8 in May, beating the forecast of 51.4 and the previous month's 51.5, according to latest figures released on Monday.

The upbeat performance of the services sector contrasted with the country's manufacturing sector. The Caixin/Markit Manufacturing PMI, released last week, fell to 49.6 in May, lower than a 50.1 forecast and April's 50.3.

"The improvement in the services sector bolstered the Chinese economy in May," said Zhengsheng Zhong, director of macroeconomic analysis at CEBM Group in an accompanying note to the data.

"However, the rapid deterioration in the manufacturing industry is worrying," he added.

— Reuters contributed to this story