China's manufacturing sector unexpectedly picked up some momentum in September despite factory employment slumping to a five and a half year low.

This fall in employment is a potential source of worry for the country's Communist leaders who prize social stability above all else.

Signs of a weakening labour market reinforced expectations that China would further relax financing conditions in coming weeks, but stop short of cutting interest rates or loosening the reserve requirement for all banks to support the economy.

The HSBC/Markit Flash China Purchasing Managers' Index (PMI) rose to 50.5 in September from August's final reading of 50.2.

This was slightly above the 50 mark separating expansion from contraction which had been expected by economists in a Reuters poll.

Economists' bets that there would be no overt policy easing are in line with remarks by senior leaders such as Finance Minister Lou Jiwei, who said over the weekend that China would not dramatically alter its policy based on any one indicator.

But the government's promises to desist from ramping up credit supply are increasingly being tested by a run of data showing that the world's second-biggest economy is sliding into a deeper slowdown, dragged by a cooling housing sector.

Today's PMI showed a measure of employment shed more than a point to drop to 46.9, its lowest since February 2009 during the global financial crisis, when a collapse in exports threw tens of millions of Chinese out of work.

A hefty drop in employment could raise alarm bells for the government, which has indicated it will tolerate slower economic growth below 7.5% for the year as long as employment is not affected.