Global mining giant BHP Billiton said Wednesday it had agreed to sell its stake in the proposed Browse liquefied natural gas project in Australia to PetroChina for US$1.63 billion.

The Anglo-Australian miner will offload its 8.33 percent interest in the East Browse joint venture and 20 percent stake in the West Browse joint venture, both located off the West Australian coast.

"This is an excellent opportunity for both companies," said the head of BHP's petroleum unit, J Michael Yeager.

"PetroChina has acquired an interest in a world class gas resource and BHP Billiton has exited a non-strategic asset."

The cash sale to China's largest listed oil producer by market value remains subject to regulatory approval, but is expected to be completed in the first half of calendar 2013.

The massive Browse liquefied natural gas project, operated by Woodside Petroleum, is expected to produce up to 50 million tonnes of LNG a year -- more than twice Australia's current total exports.

It has yet to start construction and will not begin shipping cargoes until 2018 at the earliest.