A World Trade Organization panel has concluded that China's tight control over credit- and debit-card transactions discriminates against U.S. companies, a decision considered to bring new business opportunities for U.S. companies in China's fast-growing payments market.

The WTO dispute panel found China hasn’t offered equal treatment to foreign credit-card and debit-card issuers in access to its domestic electronic-payments market, and called for China to end restrictions against foreign issuers and banks.

"The WTO panel agrees that China's pervasive and discriminatory measures deny a level playing field to American service providers," U.S. Trade Representative Ron Kirk was quoted as saying.

A spokesman for U.S. MasterCard Inc. who was not named told the Wall Street Journal that the decision makes opportunities in China "all the more interesting."

Shen Danyang, spokesman for China's Ministry of Commerce, said in a statement that the government will assess the report and will do appropriate follow-up work on the case according to the WTO's dispute resolution process.

The panel has rejected several claims by the U.S. including one that state-controlled China UnionPay Co. operates a monopoly, as well as calls for foreign service providers to be able to offer cross-border electronic payment services , according to the ministry’s statement.

Either country has 60 days to appeal the WTO's decision.

The Journal said the Obama administration challenged the rules in 2010, arguing that China UnionPay had a virtual monopoly on local-currency electronic payment services to the detriment of U.S. firms such as Visa Inc. and MasterCard Inc. 

It said U.S. payments networks have been trying to partner with China UnionPay and Chinese banks. Currently, they must partner with Chinese card issuers to offer co-branded cards, allowing China UnionPay to process domestic transactions, it said.

The Journal said more than 2.4 billion credit and debit cards were circulated in China at the end of 2010, more than twice as many as in the U.S., according to Mercator Advisory Group, a payments research firm.

It also said there were more than 3.1 billion bank cards outstanding at the end of March, with spending on those cards exceeding 84 trillion yuan ($13 trillion), according to the People's Bank of China.