MEXICO CITY, July 30 (Reuters) - Grupo Mexico, a major

copper producer, said it maintains a "very positive" long-term

outlook for copper growth in Asia, a top executive said on

Wednesday, shortly after Washington signed an order imposing 50%

tariffs on imports of the red metal.

Speaking in a call with analysts, Leonardo Contreras,

finance chief of Grupo Mexico's mining division, said the

company continues to monitor global changes before it decides

whether it should reopen a mothballed smelting project in

Arizona.