SEOUL, South Korea, Aug 25, SPA -- South Korea and China have agreed to cooperate to prevent a possible nuclear test by North Korea, South Korea's presidential security adviser said Friday, according to a news report. A nuclear test by the communist North would be «a grave situation of a different level from missile launches,»said Song Min-soon, returning from a two-day trip to China, South Korea's Yonhap news agency reported. «South Korea and China have agreed to continuecooperation not to let that situation occur,» Song wasquoted as saying.--SPA www.spa.gov.sa/384881