UnitedHealth Group will spend about $4.9 billion to buy a Brazilian health benefits and hospital services provider, as the largest U.S. health insurer takes a big leap toward international growth.

UnitedHealth, based in Minnetonka, Minn., says it will acquire about 90 percent of the outstanding shares of Amil Participacoes SA. The purchase price drops to $4.3 billion when counting Brazilian tax benefits.

Amil Participacoes provides health and dental benefits and runs a care delivery network that includes 22 hospitals. UnitedHealth says it serves more than 5 million people.

UnitedHealth currently operates in 70 countries, and its services include expatriate coverage for people living outside their home countries. But a spokesman says the insurer's international operations are a relatively small slice of its total business.