The surge in profitability reflects stronger manufacturing and sales conditions, as well as lower operating costs, said He Ping, a senior NBS economist.

"Industrial output in August rose 10.4 percent year-on-year, hitting a monthly high for 2013. Meanwhile, the corresponding cost for every 100 yuan worth of core business was 86.28 yuan, down by 0.79 yuan compared with July," He said.

The manufacturing sector, which accounts for one-third of the country's economic output, has grappled with weaker growth since last year as demand shrank.

But since August, China has seen a broad-based recovery in major economic indicators, boding well for the economy's prospects for the remainder of the year and prompting several foreign banks to raise their forecasts for 2013 GDP growth.

These latest figures are in line with earlier predictions that the government may still accelerate investment projects and cut interest rates, among other efforts, to defend a 7.5-percent GDP growth target, according to Michael McDonough, global head of economics at Bloomberg LP.

"Our current GDP growth forecast of 7.5 percent for both Q3 and 2013 may have more upside, particularly if the export recovery holds up," wrote Wang Tao, chief China economist at UBS AG, in a September note.

Shares of industrial companies bounced back on Friday, lifted by the promising data. Aluminum Corp of China was up by the 10-percent limit in Shanghai. Yanzhou Coal Mining Co jumped 4.08 percent, while giant China Shenhua Energy Co Ltd edged up 0.42 percent.