BEIJING (Reuters) - Profit growth in China’s industrial firms slowed sharply as some key manufacturing sectors stumbled on weak activity and rising debt, suggesting the world’s second-biggest economy remains underpowered despite emerging signs of stability.

Pedestrians cast their shadows on a wall at a construction site in Beijing December 12, 2014. REUTERS/Kim Kyung-Hoon/File Photo

The September data from National Bureau of Statistics (NBS) underlined the daunting task facing policy makers as the nation’s vast manufacturing industry grapples with slack demand, overcapacity and ballooning debt.

Industrial sector profits last month rose 7.7 percent to 577.1 billion yuan, slowing markedly after surging 19.5 percent in August, NBS figures released on its website showed on Thursday.

Earnings in industries such as electronics, steel and electricity were hit by a significant drop in growth, He Ping, a NBS official said in a note accompanying the data.

“Although industrial profits have got back on track with more stable growth, unfavorable factors still exist,” He said, noting weak demand at both home and aboard, and delayed payments put a strain on firms’ cash flow.

The official also cautioned about rising debt levels in the coal and steel sectors, stressing the importance of controlling debt risks as capacity cuts and structural reforms get implemented.

China’s debt has soared to 250 percent of GDP and the Bank for International Settlements (BIS) warned in September that a banking crisis was looming in the next three years.

Recent data showed some signs of stability, with annual economic growth of 6.7 percent in the third quarter matching the previous quarter, as increased government spending and a property boom offset stubbornly weak exports.

But the profits data suggest China’s economy continues to face a host of challenges as authorities try to wean businesses off cheap credit-fueled growth, temper a surge in home prices and curb rising debt levels and shadow banking activity.

“If you look at the structure of the economy, it’s actually worsening because the growth of SOEs and public sector growth is relatively stronger, but private sector growth is much weaker. This shows the quality of the growth is deteriorating,” said Yang Zhao, economist at Nomura.

OUTLOOK SUBDUED

Profits in electricity tumbled 23.2 percent on-year, as electricity prices were adjusted lower and revenue growth slowed. Earnings in general and special equipment manufacturing also turned negative, dropping 10.8 percent on-year.

Total profits for the first nine months stood at 4.64 trillion yuan ($684.77 billion), up 8.4 percent from the same period a year ago, the same pace as in the January to August period.

Industrial overcapacity, mainly in the traditional sectors, have been a drag on profits in recent months and analysts say the outlook for earnings in the sector could hinge on the progress made by policy makers to cut capacity.

Beijing has embarked on a campaign to cut capacity in the coal and steel sectors in the economy’s most significant transformation in two decades.

The August profit growth - the fastest pace in three years - was helped by Beijing’s splurge on infrastructure projects and a booming real estate industry and so was seen as unsustainable.

China’s producer prices rose in September for the first time in nearly five years, thanks to higher commodity prices.

“Profits were largely driven by a restoration in commodity prices such as coal and steel,” David Qu, economist at ANZ said in Shanghai.

But Qu said the outlook for steel prices remain cloudy, as “the tightening in the property market means potential demand could shrink.” .

Indeed, a subdued property market is expected to drag on growth in the first two quarters next year, as policy makers introduce curbs to cool home prices.

“We are optimistic that stable growth will last through end of this year, because they have to finish the projects started earlier,” said Merchants Securities economist Xie Yaxuan in Shenzhen.

“But property and its related industries will definitely affect growth in the first or second quarter next year,” Xie said.