Bai Zhongren, the president of Chinese state-owned contractor China Railway Group, has died suddenly.

The company, which ranked as the third largest contractor in the world in the 2013 Global Top 200 with revenues of US$ 74.6 billion, said in a press released issued on Sunday that Mr Bai died in an accident. However, local media reported the 53 year-old executive committed suicide.

According to Chinese media he had suffered depression in recent months, as his company's debt grew out of control. As of October 2013, the company's outstanding debt reached 531.9 billion yuan ($87.88 billion), while its assets were worth 626.5 billion yuan - a debt-to-asset ratio of nearly 85 percent.

Other sources pointed out that since China Railway Group Ltd. is a state-owned enterprise, the theory doesn't make sense. Most executives of state-owned enterprises are bureaucrats and Communist Party officials who only assume the leadership of these companies for a few years before moving on to other posts.

China Railway Group said Mr Bai's duties would be taken on by chairman Changjin Li in the meantime as it looked for an acting president.

Mr Bai had not been implicated in any safety or corruption investigations after a high-speed rail crash in Wenzhou, in eastern China in July 2011 killed 40 people.