MEXICO CITY, Oct 21 (Reuters) - Mexican steelmaker Altos Hornos de Mexico (AHMSA) confirmed on Thursday that it is exploring the possibility of filing for Chapter 11 bankruptcy protection under U.S. law for its subsidiary Minera del Norte.

The unit had been hurt by state power utility Comision Federal de Electricidad (CFE)'s decision to cancel coal supply contracts for power stations, AHMSA said in a statement, adding that a third of the mining operations were in the United States. (Reporting by Noe Torres; Writing by Stefanie Eschenbacher)