Grupo Mexico, one of the world's largest copper producers, is nearing a deal to acquire Mitsui & Co.'s 25 percent stake in the Silver Bell copper mine in Arizona for about $120 million, according to people familiar with the matter.

The Wall Street Journal reported that the deal, if it proceeds, would give Grupo Mexico sole ownership of the mine, allowing it to take full advantage of Silver Bell's output at a time when copper prices are up about 11 percent from their March lows amid signs of strengthening demand for the widely used industrial metal.

Silver Bell, located in Marana, Arizona, produces about 46 million pounds of copper annually, according to the latest available figures. Grupo Mexico's ASARCO unit owns 75 percent of the mine and Mitsui, a large Japanese trading company, owns the remaining 25 percent. ASARCO operates three copper mines in Arizona, producing a combined 350 million to 400 million pounds of copper a year.