The largest U.S. health insurer is expanding deeper into South America by spending about $2.8 billion to buy a health care provider and insurer that operates in Chile, Columbia and Peru.

UnitedHealth Group Inc. said Friday that it will start an offer next week to buy all outstanding shares of Empresas BanmĂ©dica. The insurer expects to complete the deal in next year’s first quarter.

Minnetonka, Minnesota-based UnitedHealth covers nearly 45 million people in the U.S. and another 4 million people internationally.

That includes business in Brazil, where the insurer offers health and dental benefits and hospital and clinical services.

U.S. health insurance is still the main business for UnitedHealth. It offers employer-sponsored commercial coverage and is a big provider of Medicare Advantage plans, which are privately run versions of the government’s Medicare program. But the insurer also has expanded well beyond that focus. Its Optum segment operates one of the nation’s largest pharmacy benefit management businesses and also runs clinics and urgent care and surgery centers.

UnitedHealth said earlier this month that it would spend almost $5 billion to buy nearly 300 primary and specialty care clinics and some urgent care and surgery centers from DaVita Inc. That deal will extend UnitedHealth’s health care services business into several more states.

UnitedHealth leaders said last month that health systems around the world face the same challenges of access, affordability and improving patient care, and the company would look to enter new markets.