Chinese regulators will allow foreign firms access to the yuan-denominated credit card clearing business from August next year, Hong Kong's South China Morning Post newspaper reported on Saturday.

The paper quoted a source from China's largest credit card supplier, Goldpac Group, saying People's Bank of China (PBOC) officials had informed them of the date in September.

"When the central bank gives a date, they always follow through with that," the source, an unidentified department head, was quoted as saying.

The Post's report follows an announcement by China's cabinet, the State Council, on Wednesday that China would open up its market for clearing domestic bank card transactions.

The State Council announced that foreign firms that met its criteria could set up their own clearing companies but no date or other details were announced.

The move will effectively break state-owned China UnionPay's monopoly over the business, potentially benefiting foreign companies such as Visa Inc and Mastercard in a booming market worth more than $1 trillion a year.

China had promised to open the market after criticism from the World Trade Organisation in 2012.

The international trade watchdog upheld U.S. complaints that the U.S. bank card suppliers were discriminated against in the electronic payments market in favor of China UnionPay.

The WTO rejected a U.S. claim that UnionPay was an "across-the-board monopoly supplier" of all yuan transactions.

The PBOC has yet to comment on the date, the South China Morning Post reported.