The purchasing managers' index (PMI) for China's non-manufacturing sector dropped 0.5 percentage points in March from a month earlier to 54.5 percent, data showed on Thursday.

The index tracks activity in a number of sectors, including construction, software, aviation, railway transport and real estate, according to the National Bureau of Statistics (NBS) and the China Federation of Logistics and Purchasing (CFLP).

A PMI reading above 50 percent indicates expansion, while a reading below 50 percent reflects contraction.

The decline follows a rebound in February, when the index came up from its lowest level in more than a year in January.

However, CFLP Vice Chairman Cai Jin remains optimistic.

"The March figure shows the non-manufacturing sector is still within a range of moderate and relatively fast growth," Cai said.

He attributed the slight weakness last month mainly to a drop in business in the tourism, transport and catering sectors after high demand during the Spring Festival holiday from Jan. 31 to Feb. 6.

The index for new orders dropped 0.6 percentage points from a month earlier to 50.8 percent, the new data showed.

However, the sub-index for new export orders surged by 3.4 percentage points to 51.7 percent last month.

The index for business outlook rose 1.6 percentage points to 61.5 percent, marking strengthening corporate confidence.

Employment rebounded 0.5 percentage points to 51.4 percent, while charges also rose 0.5 percentage points to 49.5 percent.

The new figures came amid signs of a slowing Chinese economy since the beginning of the year.

The NBS said on Tuesday that the country's manufacturing PMI rebounded by 0.1 percentage points from February to 50.3 percent in March, but the rebound was by no means strong compared with a 0.8-percentage-point rise in March 2013 and 2.1 percentage points for March 2012.

The HSBC manufacturing PMI, which was also released on Tuesday, dipped to an eight-month low of 48 in March from a final reading of 48.5 in February, partly due to weakening domestic demand.

The growth of China's power consumption, a key barometer of economic activity, slowed by 1 percentage point from a year earlier to 4.5 percent in the first two months.

China's economy expanded by 7.7 percent last year, flat from a year earlier and representing the lowest growth rate since 1999. The government has set this year's growth target at 7.5 percent for a third straight year.

The NBS is scheduled to release the GDP figure for the first quarter on April 16. Many analysts have forecast that the growth rate may fall below 7.5 percent.