By Bianca Flowers

CHICAGO The United Steelworkers (USW) international president said on Monday that the union supports North American steel producer Cleveland-Cliffs' bid to acquire rival, United States Steel Corp, adding that the company is the best strategic buyer.

Cleveland-Cliffs said on Sunday that it offered to buy U.S. Steel in a cash-and-stock deal valued at $35 per share, which represented a premium of 43% to U.S. Steel's last closing price.

Cliffs went public with its offer after U.S. Steel rejected the bid as being "unreasonable" and instead announced a formal review process, saying the company received multiple bids for parts or all of its business.

"Cliffs is committed to the blast furnace segment of the steel market and U.S. Steel is not," the union's international president, Thomas Conway told Reuters in an interview. "I think they are committed to the steel industry and success."

The United Steelworker's collective bargaining agreement with U.S. Steel outlines that the company has to take union leadership voices into account for acquisition bids.

U.S. Steel has said that it received "multiple unsolicited proposals." Conway said that no other bidders have come forward to court the unions' support.

(Reporting by Bianca Flowers in Chicago; Editing by Tomasz Janowski)