BEIJING (Reuters) -Profits at China's industrial firms extended gains for a second month in September, adding to signs of a stabilising economy as the authorities launched a burst of supportive policy measures.

The 11.9% year-on-year rise came on the back of a surprise 17.2% gain in August, and follows stronger-than-expected industrial and consumption activity over September.

For the first nine months, profits slid 9% from a year earlier, narrowing from a 11.7% decline in the first eight months, data from the National Bureau of Statistics (NBS) showed on Friday.

Industrial profits recovered quarter by quarter and swung to a 7.7% growth in the July-September period from declines over the previous two quarters, NBS statistician Yu Weining said in an accompanying statement.

The September number reflects an overall improvement in domestic industrial sector operations and a continued recovery in market demand, said Zhou Maohua, an analyst at China Everbright (OTC:CHFFF) Bank, adding the slowdown in year-on-year growth was due to a high base last year.

A fall in producer prices last month indicated that some industrial firms were still cutting prices to promote sales, putting a drag on overall industrial revenues and profits, Zhou said.

The improvement in industrial profits is expected to sustain in the coming months, partly due to the lag effect in domestic macro pump-priming, he added.

China's blue chip CSI300 Index gained 0.6% after opening lower in the morning session.

A run of recent data has pointed to a steadying in the world's second-largest economy, which expanded at a faster-than-expected clip in the third quarter after a rapid loss of momentum following a brief post-COVID bounce.

Analysts attribute the stabilisation to a series of policy measures rolled out in the past few months, but the persistent weakness in the crisis-hit property sector remains a major drag on the economy and corporate earnings.

Last week, Chinese battery giant CATL reported a sharp slowdown in profit growth in the third quarter, its weakest quarter since the start of last year amid slowing demand and stiff competition.

In his first remarks on policy following third-quarter gross domestic product data, China's central bank governor Pan Gongsheng vowed to bolster the economic recovery, with a focus on expanding domestic demand while curbing financial risks.

According to a breakdown of the NBS data, state-owned firms saw earnings fall 11.5% in the first nine months, foreign firms booked a 10.5% decline and private-sector companies recorded a 3.2% slide.

Industrial profit numbers cover firms with annual revenues of at least 20 million yuan ($2.73 million) from their main operations.

($1 = 7.3150 Chinese yuan)