BEIJING, May 1  -- Chinese manufacturing business activity continued improving in April, with an important index remaining in expansion territory, official data showed on Friday.

The manufacturing purchasing managers' index (PMI), a key measure of factory activity in China, posted at 50.1 in April, unchanged from March's reading but up from 49.9 for February, according to the data released by the National Bureau of Statistics (NBS) and the China Federation of Logistics and Purchasing (CFLP).

A reading above 50 indicates expansion, while a reading below 50 represents contraction. The NBS manufacturing PMI samples 3,000 enterprises of various sizes nationwide.

Zhao Qinghe, a senior analyst with the NBS, said China's manufacturing PMIs in the last three months were lingering around the expansion/contraction threshold but some PMI sub-indices in April have shown encouraging signs.

The production sub-index posted at 52.6, the highest monthly reading since November last year, he said. The sub-index for raw material purchase prices remained below the threshold at 47.8, but it had continued rising notably since January this year, which stood at 41.9.

The sub-index for production and business activity expectations posted at 59.5, remaining in the range of relatively good sentiment, Zhao said.

"Chinese companies are cautiously optimistic over China's economic growth prospects, thanks to a string of encouraging signals in both the Chinese and global economy and a price rebound in commodities such as oil," he said.

Zhao, however, admitted the downward pressure faced by China's manufacturing sector.

Domestic and global demand is still weak. The new orders sub-index posted at 50.2 in April, unchanged from March's reading, but was lower from those of previous years on a year-on-year basis. The sub-index for new export orders fell to 48.1, the lowest monthly reading since November of 2013.

Secondly, China's manufacturing sector is still in the phase of restructuring and destocking, and some traditional industries are still plagued by overcapacity, he said.

The sub-index for the finished goods inventory posted at 48 in April, down from 48.6 in March and remained below the threshold, NBS data showed.