The combined group will offer clients and travellers “a more comprehensive range of travel management products and services”.

Doug Anderson, chief executive, American Express GBT, said: “The complementary geographical footprints of each company will improve the global scale and reach of our business, enabling us to achieve efficiencies across a best-in-class platform and accelerate growth.

“The technology roadmaps of each business provide a powerful platform from which to drive future innovation. We will deliver a superior client and traveller experience through fully-integrated travel management solutions, including booking and expense management products.”

David Radcliffe, chief executive, HRG, said: “This transaction represents a good deal for shareholders and stakeholders. I am particularly excited and heartened by American Express GBT’s reassurance that it will be utilising the best talent and technology from within both organisations to create a truly world-class, leading-edge organisation, which will bring benefits to our clients, colleagues and supplier partners alike.”

The acquisition is conditioned on receipt of antitrust and other regulatory approvals and is expected to close in the second quarter of 2018.