The premium revenue of China's insurers in the first half of the year grew rapidly to reach 1.9 trillion yuan ($285 billion), but their profitability was challenged by the gloomy stock market and rising expenses, said the insurance regulator.

Revenue from premiums across the insurance industry in the first six months increased 37.3 percent year-on-year, of which life insurance revenue rose 45 percent and that of property insurance grew 7.1 percent, the China Insurance Regulatory Commission said on Thursday.

"Chinese insurers grew quickly as they improved their business structure and paid attention to risk control," said Duan Haizhou, a deputy division chief of the information and statistics department at the CIRC.

"Life insurance revenue grew quickly as the middle class are increasingly paying attention to their health. Furthermore, investment returns of life insurance products can be competitive when the capital market is not good," said Hao Yansu, director of the School of Insurance at the Central University of Finance and Economics.

"The growth rate of property insurance in the first half is the lowest in the past 10 years," said Hao. "Auto insurance business has become more mature, and it's urgent for property insurers to have a business transformation," he added.

The insurance regulator also forecast profit declines for the insurers in the first half as their portfolio income falls because of the gloomy capital market and expenses rise.

The regulator said that total profits of the Chinese insurers would drop by 54.1 percent year-on-year to 105.6 billion yuan in the first half.

Total investment returns of the Chinese insurers in the equities markets in the first half was only 24.1 sbillion yuan, dropping by 261.2 billion yuan from the same period last year, according to the insurance regulator.

"The gloomy stock market can be the main reason for the decline in profit and investment return, and the trend will continue in the second half," said Duan.

Wang Guojun, an insurance professor at the University of International Business and Economics, said Chinese insurance companies could try global asset allocation to have good investment returns and lower risks.

"Chinese insurers can go abroad, offering insurance services as well as doing some investments," said Wang.