WASHINGTON (Reuters) - Holcim Ltd (>> Holcim Ltd), a Swiss company, and Lafarge S.A. (>> LAFARGE), which is based in Paris, on Monday won U.S. antitrust approval to merge after they agreed to divest assets, the Federal Trade Commission.

The companies agreed to divest plants, terminals and a quarry to gain approval of their $25 billion deal, the FTC said.

The companies won approval for the deal from European Union antitrust enforcers in December.

In the United States, the two companies agreed that Lafarge would sell a cement plant and quarry in Iowa as well as terminals and distribution centres in Minnesota, Wisconsin, Tennessee and Louisiana.

Lafarge said previously that it would sell its Davenport cement plant in Iowa and seven terminals along the Mississippi River to Summit Materials (>> Summit Materials Inc) for $450 million in cash plus Summit's Bettendorf, Iowa, cement terminal.

Holcim will sell slag cement plants in Chicago and New Jersey and terminals in Massachusetts, Michigan, Illinois and elsewhere. Slag cement is a specialty cement used to make more durable buildings.

The two companies - the biggest cement makers in the world - announced the megadeal in April 2014, saying it was the biggest ever merger of equals.

(This version of the story adds details of the divestiture)

(Reporting by Diane Bartz; Editing by Sandra Maler)

By Diane Bartz

Stocks treated in this article : LAFARGE, Holcim Ltd, Summit Materials Inc