Chinese banks are reporting their weakest results in years as the economy slows and interest rate liberalization speeds up, and challenges are set to continue amid rising uncertainties, analysts said.

As of Thursday, 15 of 16 Chinese listed banks had released interim results. Their total first-half net profit was up 13.6 percent year-on-year to 616.9 billion yuan ($100.8 billion).

The growth rate was markedly below the 18-percent average recorded last year, though it fell within expectations, said Guo Tianyong, director of the Research Center of the Chinese Banking Industry at the Central University of Finance and Economics.

"We predict the growth of banks' profits will stand between 10 and 15 percent this year, as economic and policy uncertainties are rising. In 2014, it might even drop to 8 or 9 percent," he said.

Industrial and Commercial Bank of China Ltd, the nation's largest lender and the world's most profitable bank, said on Thursday it achieved first-half net profit of 138.5 billion yuan, up 12.4 percent.

Bank of China Ltd made 80.7 billion yuan, up 12.9 percent, according to its interim results released on the same day.

Joint-stock lenders registered the highest increases in net profit, even as the industry as a whole experienced the lowest profit growth in nearly four years.

Bank of Beijing Co Ltd, Industrial Bank Co Ltd, Bank of Ningbo Co Ltd, Hua Xia Bank Co Ltd and China Minsheng Banking Corp all achieved profit growth rates of more than 20 percent.

Bank of China President Li Lihui said on Thursday at a news briefing in Hong Kong that the trend of narrowing net interest margins, an indicator of bank profitability, would continue as China continues freeing up interest rates.

"For us, the NIM might be stable or decline in the second half. But for the full year, it may continue to widen as long as we accelerate asset turnover and strengthen reasonable allocation of our credit resources."

The economic slowdown has also taken a toll on banks' asset quality, as 12 out of 15 listed banks reported increases in both the total of non-performing loans and their NPL ratios.

China CITIC Bank International Ltd and Industrial Bank reported the fastest rise in NPL ratios, both exceeding 0.1 percentage point.

ICBC's NPL ratio went up 0.02 percentage point to 0.87 percent, while bad loans surged 7.2 billion yuan, in contrast to the 2.1 billion yuan increase in the first half of 2012.

Only two banks reported a decrease in their NPL ratios. At Agricultural Bank of China Ltd, the ratio declined to 1.25 percent from 1.33 percent at the start of the year. At Bank of China, it fell to 0.93 percent from 0.95 percent.

The asset quality of Chinese lenders deteriorated further in the second quarter, according to the China Banking Regulatory Commission. Domestic banks' NPLs rose by 13 billion yuan, the seventh consecutive quarterly increase, while total NPLs stood at 539.5 billion yuan at the end of June, with increases across all categories.

As China's economic growth decelerates and some industry sectors grapple with growing oversupply, the risks from China's recent credit boom appear to be rising to the surface for the country's banks, Standard & Poor's Ratings Services said on Thursday.

It examined the credit profiles of China's top 50 banks by asset size and assessed the credit outlook for China's banking sector.

"Rising credit costs, compressing interest margins and growing pressures on non-interest income are likely to constitute a triple-hit to bank earnings," said Liao Qiang, S&P's senior director.

"In particular, we think it is highly likely that the banks could incur substantially higher credit losses in the coming years."

The mega banks and national banks appear to be better-placed to withstand China's economic downturn, said the report. In contrast, most smaller players are likely to experience a further weakening of capitalization, and some may even witness significantly deteriorating funding and liquidity profiles, it said.

Top banks could spearhead massive market-driven consolidation, the pace of which, however, will hinge on the severity of the present credit downturn, Liao said.

Gao Changxin in Hong Kong contributed to this story.