Visa (V.NYSE), MasterCard (MA.NYSE) and American Express (AXP.NYSE) have spoken to the US Trade Representative’s Office about a possible WTO complaint against China for shutting them out of the country’s US$723 billion payment-processing market, Bloomberg reported. Discover Financial Services (DFS.NYSE) and First Data Corp are also involved in the talks, according to people briefed on the issue. Payment-card purchases in China have grown more than 26-fold since 2002, according to Mercator Advisory Group. Card spending – not including ATM transactions – reached US$722.7 billion last year and is on course to hit US$1.2 trillion by 2012, equal to nearly half the payments Visa processed worldwide in 2009. Foreign operators are only allowed to participate in the local currency bank card market by issuing co-branded cards with Chinese institutions. All payments are executed through China UnionPay. When China joined the WTO, it promised to grant foreign access to “all payment and money-transmission services, including credit, charge and debit cards,” by December 11, 2006.