China Petrochemical Corp. (Sinopec) agreed to buy 4.3 million metric tonnes of liquefied natural gas (LNG) annually from Australia Pacific LNG for 20 years, Sinopec Group, Sinopec's parent company, said Thursday.

Sinopec Group said the gas will be delivered from Queensland, Australia to a planned gas collection station in China's Guangxi Zhuang Autonomous Region and other terminals.

Besides the gas deal starting from 2015, Sinopec also will buy 15 percent of the Australian company's shares.

Australia Pacific LNG is owned by Origin Energy Ltd. and ConocoPhillips, with each company holding 50 percent of its stakes. The Sinopec investment will reduce the two companies' stakes in Australia Pacific LNG to 42.5 percent each.

The deals are subject to the final approval of both Chinese and Australian authorities.

"The deals will help China acquire more gas supplies to meet domestic demand. Sinopec will continue to seek cooperation opportunities in Australia," said Zhang Yaocang, the company's vice general manager.

LNG is a natural gas cooled and compressed into a liquid so it can be transported by ship. This convenient delivery method has made LNG a leading choice for China's gas imports.

China imported 9.34 million metric tonnes of LNG in 2010, up 75 percent from the previous year. The country's LNG consumption will continue to increase by about 20 percent in 2011, according to Chinese energy authorities.