King & Wood Mallesons (KWM) has acted opposite Ashurst Australia on a $1.63bn (£1bn) transaction between PetroChina and BHP Billiton, marking the latest in a string of significant cross-border energy deals in Asia this year.

The deal has seen China's biggest oil and gas producer agree to buy BHP's share of the Browse liquefied natural gas (LNG) project in Western Australia, purchasing two separate stakes.

KWM advised PetroChina on the deal, with a team led by Hong Kong Partner Joshua Cole and supported by Perth-based corporate partners David Perks, Tim Warman and Sally Audeyev.

Ashurst Australia acted for BHP, with corporate partner and head of the firm's Australian M&A practice Marie McDonald overseeing a team in Melbourne.

The transaction has seen PetroChina, a subsidiary of PetroChina International Investment (Australia), buy BHP's 8.33% stake in the East joint venture (JV) and its 20% share in the West – the two JVs together making up the Browse project.

Other major shareholders in the project include Woodside, BP, Mimi and Shell, with Mimi and Shell both buying into the project earlier this year.

The deal was agreed earlier this week and, subject to regulatory approval, is expected to close in the first half of 2013.

"The acquisition is a significant strategic investment for PetroChina," said Cole. "It will enable them to participate in another major LNG facility project in Australia.

This year has seen a steady stream of North Asian investment into Australia, as countries such as China, Japan and Korea look south to boost their energy supplies from the resource-rich country.

Last month KWM acted opposite Herbert Smith Freehills on one of the most significant transactions of the year, representing BG Group in the $1.93bn (£1.22bn) sale of its 40% stake in the Queensland Curtis LNG Project to China National Offshore Oil Corporation.

Meanwhile, Australia's Allens, Allen & Overy and White & Case all advised on a deal in November that saw Japanese group Tokyo Electric Power Company take a stake in Australia's Chevron-backed Wheatstone Project in a deal valued at around $1bn (£621m).