China Southern Airlines Co may order as many as 12 more Boeing 777 freighters, said Liu Xiaoxiao, the airline's deputy general manager for cargo.

The airline plans to build a fleet of 20 freighters within five years, Liu said in an interview in Shanghai, according to Bloomberg. The carrier, based in the southern city of Guangzhou, operates two 747 freighters and announced last year an order for six 777 freighters. All of the new planes will be 777 freighters, according to Liu.

Chinese airlines and overseas carriers such as Cathay Pacific Airways Ltd have added cargo capacity in China as the country's growing exports drive demand. The nation's airlines boosted their cargo volume 11 percent last year to 3.41 million tons, the aviation regulator said on January 18.

China Southern is in talks with overseas airlines, including Air France-KLM, about forming a cargo venture, Liu said. Air France is Europe's biggest carrier.

China Southern has also spoken to US and Asia-Pacific carriers about the cargo venture, he added, without elaborating. The airline will hopefully complete talks on the joint venture within this year, Liu said.