Boeing followed through with a promise to protest against the US air force’s decision to award a refuelling tanker project to EADS, its main European rival, accusing the military of running a “fundamentally flawed” evaluation.

The air force’s decision to assign the $35bn contract to EADS and Northrop Grumman has drawn scrutiny from politicians, including Democratic presidential hopefuls Senators Barack Obama and Hillary Clinton, and renewed concerns for US job losses.