China's manufaturing sector expanded in December, with growth declined to a three-month low of 50.5, showed the preliminary reading of HSBC's purchasing managers' index (PMI) on Monday.

HSBC PMI stood at 50.8 in November and 50.9 in October.

Growth in the new order and new export order sub-indices expanded faster, while employment decreased at a faster rate compared with a month before, it said.

The December HSBC flash manufacturing PMI reading slowed slightly from November's final reading, but still stands above the average reading of the third quarter, said Qu Hongbin, chief China economist with HSBC. "This implies that the recovering trend of the manufacturing sector starting from July still holds up," he added.

"We expect China's GDP growth to stabilize at around 7.8 percent in the fourth quarter," Qu said.

After the release of the data, the benchmark Shanghai Composite Index fell 1.43 percent to end the morning session at 2,164.75. The Shenzhen Component Index declined 1.53 percent to close at 8,301.11.

The flash PMI reading only covered a shortened period from December 5 to 12. The final reading will be released on January 2, 2014.