Frustration over Chinese restrictions on foreign financial news companies escalated into a trade dispute last month when the US and the EU filed a joint formal complaint to the World Trade Organization (WTO).

The row is rooted in China’s decision two years ago to require companies such as Bloomberg, Reuters and Dow Jones to distribute their information through a branch of the state news agency, Xinhua, rather than deal directly with clients.

Xinhua’s subsequent decision to set up Xinhua 08, its own financial data unit which will compete with Western providers, was the final straw. Reuters and others fear greater restrictions to come on their provision of data.

The US trade representative Susan Schwab said that China’s treatment of non-Chinese suppliers of financial information services was restrictive and placed foreign suppliers at a serious competitive disadvantage.

“We have raised this matter with China repeatedly, yet the problem has not been resolved,” she said. “We hope the filing of our request for formal WTO consultations will lead to a swift resolution of this matter.”

China joined the WTO in 2001, but has repeatedly been accused of failing to follow the rules. The complaint will trigger a 60-day consultation period. If talks fail, the EU and US can ask the WTO to begin a formal investigation.

A Chinese official said: “We shall study the request for consultations and deal with it according to WTO procedures.”