Amex to Absorb Two Thomas Cook Units

American Express Co. said Monday it is buying the U.S. offices and the international business travel unit of London-based Thomas Cook Group Ltd. for $375 million.

American Express said it is seeking to strengthen its corporate travel business worldwide, and the two Thomas Cook businesses, with annual sales of more than $3 billion, will expand its travel management services business by a third.

The Thomas Cook Partnership is the third-largest travel agency in the United States. American Express is No. 1, even before the purchase.

Harvey Golub, chairman and chief executive of American Express, said the Thomas Cook acquisitions are part of an effort to capture a larger portion of the $400-billion international corporate travel market.

Golub said that, among other benefits of the deal, he expects to see spending on American Express corporate charge cards rise.

The purchase of Thomas Cook Group, a unit of Germany’s Westdeutsche Landesbank Gironzentrale, is final, and the agreement to buy Thomas Cook Partnership will be closed by Sept. 30, American Express said.

Roger Ballou, president of Amex Travel Services Group, said decisions on staffing and business practices for the acquired units would be made over time. He would not say if or when there will be layoffs.

The acquisition is expected to affect airlines, travel agents and business travelers but have little impact on individuals.