The European Commission also have concerns regarding the deal, saying that the deal could breach rules on restrictive practices.

The alliance would have 80% of flights from London Heathrow to Boston and 62% from Heathrow to New York JFK.

This is the second time that BA has tried to forge a partnership with AA and it has denied that the alliance would lead to higher fares for passengers.

Sir Richard Branson, the president of Virgin Atlantic, said: “Now two competition authorities have voiced their concerns over the proposed BA-AA alliance, we renew our call on the regulators to reject these anti-competitive proposals.

“The competition authorities have thoroughly scrutinised the proposals in an effort to safeguard competition in the interests of consumers. Having done so, both the authorities on opposite sides of the Atlantic have cited concerns. These concerns are absolutely justified and the alliance should not be given the go-ahead.”