China Life Insurance Company, the world's largest insurance provider by market value, has issued a profit warning for the first half of 2012 blaming volatile equity markets, and a drop in its asset values.

The company, due to publish its interim results on Aug 28, did not specify the extend of the fall, but said that it will not be any worse than the 29.4 percent fall in profits it announced in the first quarter.

In Q1, China Life reported total assets of 1.66 trillion yuan ($266 billion), a 4.3 percent year-on-year increase. Net profits were 5.63 billion yuan.

The company said low-margin products, increased competition and new rules had stalled growth, and that volatile equity markets has squeezed profit margins.

The company's market share in China was 70 percent in 2000 but that had fallen to around 33 percent by 2011, according to a recent Credit Suisse analysis.

The report added that asset devaluation may impact China Life's performance in the first half of 2012, and another loss of about 10 billion yuan from investment in the second quarter is expected.

China Life saw a 45.5 percent drop in year-on-year profits in 2011.