A merger of fiber makers was opposed by the FTC.

The Federal Trade Commission said it will ask a federal court to block American Hoechst Corp.’s proposed $2.8-billion acquisition of Celanese Corp., contending that the merger would reduce competition in the production of textile polyester fiber. The combination would become the nation’s largest producer of polyester, officials said. Celanese is based in New York and American Hoechst has headquarters in Somerville, N.J.