Long-serving Vinson & Elkins energy partner and former China practice head Xiao Yong has left the firm to join Dechert.

Xiao (pictured) is moving with a team of lawyers, all of who specialise in energy work. Xiao and associate Jason Wu will be based in Dechert's Hong Kong office, while partner Nicholas Song, counsel Zhaohui Li and associate Sarah Teh are joining the firm in Beijing.

The move is subject to a partnership vote next week.

A former government official, Xiao represents state-owned enterprises (SOEs) on outbound oil and gas deals and projects. In late 2015, he led the Vinson team representing longstanding client Sinopec on a $1.3bn (£1.1bn) deal to buy a 10% stake in Russian energy company Sibur. In addition to Sinopec, he has also advised China National Offshore Oil Corp and China National Petroleum Corp on deals in the Americas and Southeast Asia.

He joined Vinson in 1997 from Skadden Arps Slate Meagher & Flom, where he was a counsel. He made partner five years later, subsequently taking on leadership of the firm's China practice. Before joining Skadden in 1995, Xiao spent a decade as a senior official in the foreign investment law division of China's Ministry of Foreign Trade and Economic Cooperation, now known as the Ministry of Commerce.

The departures follow a sharp decline in Vinson's Asia headcount during the past five years. The Houston-based firm had as many as 40 lawyers in Asia in 2012, but this figure had dropped to 15 by 2015. Once the go-to firm for China's oil giants, Vinson has seen a drop-off in work in the region in recent years, amid falling oil prices.

A Vinson spokeswoman said the firm conducted a strategic review of the Hong Kong and Beijing offices last year, and decided to realign its China practice to be more consistent with the firm's global strategy. The two offices will now focus on practices including private equity and special situations, energy projects for global clients, international dispute resolution, governmental investigations and intellectual property.

Vinson opened a fourth Asian office in Taipei last year, focusing on intellectual property and technology work. In 2013, the firm closed its Shanghai office to focus on Beijing-based SOE clients, while former Shanghai managing partner David Blumental – who joined the firm alongside Xiao from Skadden – left for Latham & Watkins in 2014.

Meanwhile, last year partners James Cuclis and David Lang both relocated back to Houston from Hong Kong.