Hogg Robinson stepped up its presence in America with the purchase of Robustelli World Travel.
The agency said it planned a US purchase after parting company with its partner BCD Holdings, with which it jointly owned the BTI brand, earlier this year.
Robustelli World Travel was founded in 1965 by American football star Andy Robustelli and is based in Stamford, Connecticut.
It will trade as Hogg Robinson Robustelli and alongside Hogg's previous American acquisition, New York-based Sea Gate which it bought last year.
The acquisition of Robustelli places Hogg as the fifth largest travel management company in America.
Robustelli has a strong presence in meeting and event planning and in sports travel management, two areas where Hogg sees opportunities for expansion.
Robustelli's executive management team led by Rick Robustelli, Paul Salvatore and Dan DeFrancesco will join Sea Gate executives to form Hogg's new integrated senior management team in the USA.
Hogg has indicated it is still interested in more purchases in America. There are also likely to be acquisitions in The Netherlands and Belgium where, after its split with BCD, there are gaps in its network.
Hogg has wholly owned operations in 20 countries all trading as BTI. It has partnerships in a further 80 countries.
David Radcliffe, Hogg's ceo, said: "We are particularly delighted… to welcome a company to the Hogg Robinson group with the prestigious reputation of Robustelli whose client focused approach, existing international experience and local knowledge will further strengthen our North American presence.
"The coming together of Sea Gate and Robustelli are the start of an exciting expansion programme in North America where we anticipate making further announcements in due course."
Dan Green, ceo of Hogg Robinson Sea Gate, said: "Robustelli is a perfect match in terms of operating culture and its focus on delivering value to the client."
Paul Salvatore, ceo of Robustelli, said: "These are exciting times for our clients. Hogg Robinson is a respected company with exceptional global capabilities and we are delighted to be joining them."