PHILADELPHIA—CIGNA Corp. is acquiring a European provider of expatriate benefits for an undisclosed sum.

Based in Antwerp, Belgium, Vanbreda International N.V. specializes in providing worldwide medical insurance and employee benefits programs to intergovernmental and nongovernmental organizations, including international humanitarian organizations, as well as corporate clients. It has more than 400 employees in offices throughout Europe, the Middle East, Africa, Asia, Latin America and in the United States.

The acquisition of Vanbreda will enable Philadelphia-based CIGNA to grow its employee benefits business globally, according to William L. Atwell, president of CIGNA International, in a statement. And because Vanbreda has a growing portfolio of international individual business, the acquisition will enable CIGNA to expand into that market as well, he said.

Together, CIGNA and Vanbreda International’s international employee benefit programs will cover approximately 700,000 expatriates worldwide.

Vanbreda International will continue to operate as an independent business under the existing leadership of Rudi Bertels, CEO, and Wouter Reggers, chief operating officer.

UBS Investment Bank, a division of Zurich, Switzerland-based UBS A.G., served as CIGNA’s sole financial adviser on the transaction. Financial details of the acquisition were not disclosed.