Travel trade union the Transport Salaried Staffs’ Association has called on the UK’s competition authorities to investigate consolidation among the big four fearing the remaining two firms would “dominate the market”.

Thomson and First Choice have announced a merger hot on the heels of a deal between Thomas Cook and MyTravel.

TSSA general secretary Gerry Doherty urged the Competition Commission to review the mergers.

“There is no question this will mean less choice for travellers,” he said. “We are now left with just two giant firms dominating the market.”

He also feared there would be mass shop closures on the high street.

“It’s now time for the Competition Commission to look at the travel industry,” he said. “We need to examine what this means for customer choice and prices in the long term.”