The Chinese government is investigating China Telecom and China Unicom, the country’s two main fixed-line carriers, over claims that they behaved like monopolies, in a rare high-profile move against state-owned enterprises.

The two groups were trying to keep competitors out of the internet access market by demanding prohibitive prices for leasing their networks, according to a senior official at the government department in charge of the pricing aspects of China’s anti-monopoly law.

If these findings are confirmed, the companies could be fined up to 10 per cent of their broadband revenues for 2010. Li Qing, deputy director of the price supervision and anti-monopoly bureau under the National Development and Reform Commission, said that China Telecom’s revenues in the broadband business were about Rmb50bn ($7.9bn) last year, and China Unicom’s about Rmb30bn. “In the market for internet access, China Telecom and China Unicom combined account for more than two-thirds of the market,” Ms Li said on a news programme on China Central Television, the national broadcaster.