The purchasing managers' index (PMI) for China's manufacturing sector stood at 50.2 in December, unchanged from November, the National Bureau of Statistics (NBS) said Tuesday.

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

This marks the second straight month of expansion, partly buoyed by booming supply and demand as well as increasing export orders, said NBS senior statistician Zhao Qinghe.

On a month-on-month basis, the sub-index for production gained 0.6 points to 53.2 in December, signaling faster expansion, while that for new orders fell slightly to 51.2, still in the expansion zone.

Imports and exports were improving in December, said Zhao, as the sub-index for new export orders gained 1.5 points to 50.3, the first expansion since June 2018. The sub-index for imports climbed 0.1 point month on month to 49.9.

PMI of mid-sized enterprises went up 1.9 points from the previous month to 51.4, while that of big enterprises fell slightly to 50.6.

In December, PMI of high-tech manufacturing, equipment manufacturing and consumer goods all rose for the third straight month, showing accelerated transformation and upgrades, said Zhao.

Tuesday's data also showed China's composite PMI slid slightly to 53.4, but was 0.3 points higher than this year's average, indicating steady expansion in the production of China's companies.