Manufacturing activity hit a four-month high, according to the preliminary findings of a key index.

The HSBC Purchasing Managers' Index rose in August to 50.1 from 47.7 in July. A reading above 50 indicates expansion.

A sub-index indicating factory output went up to 50.6 in August from 48.0 in July, the highest level in three months.

"China's manufacturing growth has started to stabilize on the back of modest improvements of new business and output," said Qu Hongbin, chief China economist in with HSBC.

The August growth was mainly driven by recent measures and company restocking, despite weakness in external demand, Qu said.

"We expect further filtering-through, which is likely to deliver some upside surprises to China's growth in the coming months."