(Adds share price move, value of unit)
MEXICO CITY, Feb 3 (Reuters) - Mexican metals miner and railroad operator Grupo Mexico said it was considering a public offering for about 15 pct of its rail business.
The offering would be carried out by a firm spun off from Infraestructura y Transportes Mexico (ITM), Grupo Mexico's transportation unit, the company said in a statement to Mexico's bourse on Tuesday.
The proposal is already under review by Mexico's banking and securities regulator, but "the details of the offering are still being analyzed," the company said.
ITM would transfer some of its assets, liabilities and capital to the spin-off, including shares of Grupo Ferroviario Mexicano and Infraestructura y Transporte Ferroviario, Grupo Mexico said in a separate statement to the exchange.
Grupo Mexico has been under fire after a toxic leak in August at its Buenavista copper mine released mining acid into the Bacanuchi River in the northern state of Sonora, prompting calls for massive fines and an end to its concession there.
The company managed to avoid losing its concession to run one of the biggest copper mines in the world by bowing to government demands that it fund a multimillion-dollar cleanup of the spill site.
At the close of the third quarter last year, Grupo Mexico's ITM unit reported net earnings of $89.8 million and assets worth about $3.4 billion.
Grupo Mexico shares closed up 3.6 percent at 41.01 pesos on Tuesday. (Reporting by Alexandra Alper and Tomas Sarmiento; Editing by Gopakumar Warrier)