China announced a currency swap with Pakistan on Saturday in a new step to gradually expand use of its tightly controlled yuan abroad. The Chinese central bank said it has agreed with its Pakistani counterpart to swap 10 billion yuan ($1.6 billion) for 140 billion Pakistani rupees. It said the money would promote investment and trade but gave no details of how it would be used. Such agreements give central banks access to each other''s currency but commercial banks still need to create systems to issue letters of credit and handle other transactions in those currencies before companies can use them. Since the onset of the global financial crisis in late 2008, China has signed currency swap agreements with 14 countries and regions.