China Oilfield Services Limited (COSL), the largest oilfield service provider in Asia, has issued corporate bonds valued at 1.5 billion yuan ahead of an expected listing on the mainland stock market, according to a report on Xinhua. It is the first time COSL, and its parent company, China National Offshore Oil Corporation (CNOOC), the country's largest offshore oil producer, has issued corporate bonds on the mainland market. The 15-year bonds have an interest rate of 4.48 percent and have been classified as "AAA", the highest rating, by the Dagong Global Credit Rating. They were issued four days before the central bank announced a rise in interest rates and took four days to sell out.