The exchange, the world's oldest and largest market for industrial metals, in April lifted Williamson from a non-executive director to interim chairman after incumbent Gay Huey Evans stepped down.

Williamson is taking on the role immediately under a contract lasting until April 2026, the exchange said in a statement.

"We will continue to focus on measures that will advance the market's structure, keeping the LME competitive and attractive, driving liquidity, and supporting our members and customers as they deliver their own success," Williamson said.

LME nickel volumes have improved but remain significantly below levels seen early last year before a trading crisis sank interest in the benchmark.

A chaotic spike in nickel prices in March last year forced the LME to shut the market and spurred lawsuits by financial players who said they lost out when trades were cancelled.

Williamson served on the board of Hong Kong Exchanges and Clearing, owner of the 146-year old LME, from 2008 to 2021 as non-executive director. He was appointed to the LME board in September 2021.

(Reporting by Eric Onstad, editing by David Evans)