BEIJING - A state-owned high-speed rail operator between Beijing and Shanghai reported net profits of 6.58 billion yuan ($982 million) for 2015, a shareholder document showed.

Beijing-Shanghai High-Speed Railway Co has never disclosed its earnings before. Its 2015 figures were made public after a shareholder released a document on Monday, revealing the firm's profit data.

A bond prospectus released by Tianjin Railway Construction Co, a shareholder of Beijing-Shanghai High-Speed Railway Co, showed that the total assets of the company amounted 181.54 billion yuan at the end of last year, with the total liabilities standing at 50.37 billion yuan.

In 2015, the gross revenue of the company was 23.42 billion yuan, and its total operating costs hit 16.74 billion yuan.

Known as the "the world's most profitable high-speed rail," the Beijing-Shanghai high-speed railway covers more than 1,300 km within five hours.

It transported 130 million passengers in 2015, with the profit per customer coming to around 50 yuan.

Although the railway authority has said that the Beijing-Shanghai high-speed railway was the only profitable high-speed rail in China in the past five years, some believe that other lines in densely-populated and developed regions will likely become profitable soon.