Allen & Overy (A&O) City arbitration partner Jeffrey Sullivan is set to join Gibson Dunn & Crutcher.

Sullivan will join Gibson Dunn's international arbitration team as a partner in London. He has spent more than a decade at A&O, making partner at the magic circle firm in 2013.

He specialises in international commercial and investment treaty arbitration and is both UK and US qualified.

While at A&O, he advised more than 25 investors on eight arbitration claims against Spain relating to the regulation of the Spanish renewable energy sector, involving claims worth more than €2.5bn (£2.2bn).

He also previously spent five years as an associate at US law firm Foley & Lardner.

Gibson Dunn chairman and managing partner Ken Doran said: "Given the prevalence of investment treaty disputes and the inclusion of arbitration clauses in large commercial transactions and investment ventures, we believe this is an area of increasing importance to our clients."

Gibson Dunn has been on a recruitment spree in Europe in recent months. In June, the US firm hired Herbert Smith Freehills global energy co-head Anna Howell in London, while the same month, it recruited four partners and one counsel from Ashurst's Paris base.

Meanwhile, A&O has focused predominantly on lateral hires in the US. Earlier this year, the firm recruited a three-partner New York finance and securities team from Paul Hastings, as well as a former federal prosecutor at the Southern District US Attorney's office from white-collar boutique Morvillo.