MEXICO CITY - Former workers of Mexican miner Grupo Mexico plan to block access to the giant Buenavista copper mine on December 1 to pressure the company and the country's incoming leftist government to give them back their collective labor contracts.

The planned industrial action is part of a longstanding dispute after Grupo Mexico fired the mine's workforce and reopened it in 2010, following a federal judge's ruling that a nearly three-year strike over a labor dispute was illegal.

"We're looking to recover our collective labor contracts, which was stolen by Grupo Mexico," Sergio Tolano, secretary general of section 65 of the National Mining Union, told Reuters.

Tolano said the section's 650 members plan to block access roads to the Buenavista del Cobre mine, located some 40 km south of the Arizona border in Sonora state, on December 1 as President-elect Andres Manuel Lopez Obrador begins a six-year term in office.

"Now we have a new incoming government that backs workers," Tolano said.

Grupo Mexico said any move to block roads to its mine would be illegal.

"They have not worked for us for many years and the labor relationship was dissolved by an order the federal arbitration conciliation board issued in 2009," said Jorge Lazalde, Grupo Mexico's general counsel.

"Obviously, if they break the law, they'll have to face the consequences," Lazalde said.

The mining sector was already on high alert after a lawmaker from Lopez Obrador's National Regeneration Movement (Morena) party presented a Bill on Tuesday that analysts said could hinder mining operations, hitting shares in Grupo Mexico and other firms.

The Bill would require the consent of indigenous communities before granting mining concessions on their land.

Mexican equities and the peso currency have been rattled in recent weeks by another Morena-backed proposal to cut bank fees, as well as a decision by Lopez Obrador to scrap a partly built airport for the capital.

The moves have stoked fears among investors about how Lopez Obrador will steer Latin America's second-biggest economy after he takes office.