flickr / Images_of_Money According to Reuters:

Bank of China, a big market-maker in China's onshore foreign exchange market, has stopped foreign exchange forwards and swaps trading with several European banks due to the unfolding debt crisis in Europe, three sources with direct knowledge of the matter told Reuters on Tuesday.

The European banks include French lenders Societe Generale, Credit Agricole and BNP Paribas (BNPP.PA), and Bank of China halted trading with them partly because of the downgrading from Moody's, the sources said.

Another Chinese bank said it had stopped trading yuan interest rate swaps with European banks.

According to one source, "Apart from spot trading, all swaps and forwards trading (with the European banks) have been stopped."

Reuters was unable to reach SocGen, Credit Agricole, or BNP for comment.