BEIJING, Feb. 1 -- China's service sector activity dropped in January, an official monthly survey showed on Sunday.

The purchasing managers' index (PMI) for the non-manufacturing sector retreated to 53.7 in January from 54.1 in December, according to a report released jointly by the National Bureau of Statistics and the China Federation of Logistics and Purchasing.

A reading above 50 indicates expansion, while a reading below 50 represents contraction.