Activity in China's service sector expanded at its slowest pace in two-and-a-half years in January, suggesting weaker demand during the first month of 2014, a private survey showed on Friday.

HSBC Holdings Plc released the Purchasing Managers' Index for services, which eased to 50.7 in January from 50.9 in December.

The official PMI for the service sector - calculated by the China Federation of Logistics and Purchasing and National Bureau of Statistics - was at a five-month low of 53.4 in January, down from 54.6 a month earlier.