Grupo Mexico and its subsidiaries dodged losing a concession to run one of the biggest copper mines in the world as long as they comply with government obligations that include creating a $151 million clean-up fund, following a toxic spill.

The fund is far bigger than a $23 million reserve that Grupo Mexico had previously set aside for the clean-up at Buenavista copper mine. The government said Grupo Mexico could face fines totaling $3.37 million.

"If they meet obligations set by the authorities, production will continue," Economy Minister Ildefonso Guajardo told a news conference.

Shares in Grupo Mexico slightly pared losses following the announcement, to trade down 0.47 percent at 46.37 pesos a share.

A toxic leak released 40,000 cubic meters of mining acid into the Bacanuchi River in the northern state of Sonora last month, leading critics to call for massive fines against the company and even an end to its Buenavista concession.

Grupo Mexico said last week that the mine was operating normally after the spill and reaffirmed its overall copper output for this year at 850,000 tons.

The company is in the midst of a $3.4 billion expansion project at the mine, which has the largest proven copper reserves in the world. The expansion aims to boost production capacity to 1.3 million tons by 2017.