NASHVILLE (AP) — Tennessee is joining a federal lawsuit to stop the merger of major health insurance companies.

State Attorney General Herbert Slatery says in a release Thursday that the move by Blue Cross-Blue Shield insurer Anthem to acquire Cigna would reduce competition in Tennessee and could affect benefits, premiums and care.

The other states joining the lawsuit are California, Colorado, Connecticut, Georgia, Iowa, Maryland, Maine, New Hampshire, New York, and Virginia, plus the District of Columbia.

The federal lawsuit seeks to block the combination of Anthem and Cigna, along with the proposed merger of Aetna and Humana.

Industry experts say the impact on consumers would take years to materialize and could offer savings in some areas, along with the risk of higher costs elsewhere.

The companies plan to fight the lawsuit.