BEIJING (AFX-ASIA) – China Petroleum & Chemical Corp (Sinopec) (SHA 600028; HK 0386; NYSE SNP) and PetroChina Co Ltd (HK 0857; NYSE PTR), the country’s two biggest oil producers, have begun slashing refined-oil prices in a price war to win market share in western China’s Chongqing municipality, the 21st Century Business Herald reported, citing sources…