2 MIN. DE LECTURA
(Adds quote from prosecutor, environment minister, background)
MEXICO CITY, Aug 26 (Reuters) - Mexican metals miner and railroad operator Grupo Mexico could face a bill running into billions of pesos to clean up a toxic spill that could prove to be the country's worst mining disaster in modern times, the government said on Tuesday.
Grupo Mexico could face an initial fine of 40 million pesos ($3.05 million) over the spill into a river near the Buenavista copper mine in the northern state of Sonora, Mexico's environmental prosecutor Guillermo Haro said.
The company is in the midst of a $3.4 billion expansion project at the mine, which was formerly known as Cananea and has the largest proven copper reserves in the world. The expansion aims to boost production capacity to 1.3 million tonnes by 2017.
Haro's office says Grupo Mexico pumped 40,000 cubic meters of toxic mining acid into the Bacanuchi river. It said the clean up of the spill "could run into hundreds of millions or even billions of pesos".
Shares in Grupo Mexico rose 1.24 percent on Tuesday at 47.21 pesos per share following news of the scale of the potential fine.
The spill could be "the worst environmental disaster in the country's mining industry in modern times," Environment Minister Juan Jose Guerra told reporters.
Last week, Mexico's Congress urged the government to cancel Grupo Mexico's concession to operate the mine. (1 US dollar = 13.1063 Mexican peso) (Reporting by Tomas Sarmiento; Writing by David Alire Garcia; Editing by Simon Gardner and Andrew Hay)