Gibson Dunn & Crutcher has stopped lobbying on behalf of Saudi Arabia against US legislation affecting oil-producing countries, becoming the latest firm to end ties with the kingdom amid international outcry over the alleged killing of dissident Saudi journalist Jamal Khashoggi.

Three Gibson Dunn lawyers – including high-profile litigator Ted Olson – were named in August on a $250,000 flat-fee lobbying contract for the kingdom, and the advocacy included the preparation of a whitepaper opposing the passage of the No Oil Producing and Exporting Cartels Act, widely known as NOPEC.