China will merge its three biggest freight airlines and build the combined entity into Asia's largest air cargo operator, a top aviation official was reported as saying. "Currently, this work [the merger] is being actively pushed," the official Xinhua news agency quoted Zhou Laizhen, deputy chief of the Civil Aviation Administration of China (CAAC) as telling an industry forum. China's top-three cargo operators are the freight arm of Beijing-based flag carrier Air China, Shanghai-based China Cargo Airlines and China Southern Airlines Cargo, headquartered in the southern city of Guangzhou, said the report. China has the world's second-largest air transport system, but its cargo flight throughput grew just 7.8 percent last year to 135.6 million tons. According to International Air Transport Association statistics, Asia's biggest cargo airline by freight ton kilometers in 2014 was Hong Kong-based Cathay Pacific, followed by Korean Air. Worldwide, Cathay Pacific and Korean Air were number two and number three, respectively, behind global leader Emirates.