Bank of China has stopped dealing with some European banks on a series of ordinary currency transactions in the Chinese market because of concerns about mounting financial risks in Europe, according to two sources with knowledge of the matter.

The halt by Bank of China, the biggest Chinese foreign exchange lender, is unlikely to have a serious impact on the operations of the European banks in China, let alone internationally, but it is a potent reminder of Beijing’s determination to steer clear of entanglement in global market troubles.

China has repeatedly expressed support for the euro and vowed to buy bonds issued by indebted European nations. However, the action in the domestic foreign exchange market reveals growing Chinese nervousness about European fiscal health.