Mayer Brown and Freshfields Bruckhaus Deringer have won roles on the planned $4.2bn (£2.6bn) merger of former BP chief executive Tony Hayward’s investment vehicle Vallares with Turkish oil company Genel Energy International.

Mayer Brown’s London office is advising Genel, the largest oil producer in the Kurdistan region of Iraq, fielding a team led by global energy co-head Robert Hamill, working with partners including Kate Ball-Dodd and Richard Smith (corporate), James Hill (tax) and Mark Compton (financial services).