MEXICO CITY (Reuters) -A 2014 toxic spill in a Mexican river blamed on Grupo Mexico was not an accident but a result of negligence, the country's environment minister said on Thursday, while urging the mining conglomerate to create a new plan to remediate the damage.

"It was not an accident, it was negligence," Environment Minister Maria Luisa Albores said, adding that the government filed a complaint in August against the company, one of the world's largest copper producers.

Grupo Mexico failed to remediate the river's water and soil and did not provide the funds to carry out proper works for the environmental recovery of the area, according to Albores.

The company needed to provide an initial 2 billion pesos ($111.86 million), of which it only provided half, she said.

The spill was first detected on the morning of Aug. 6, 2014 and pumped 40,000 cubic meters (over 10 million gallons) of toxic mining acid into the Bacanuchi river in Mexico's northern Sonora state, the federal attorney general's office for environmental protection (Profepa) said at the time.

The possible fine for the spill was set at up to 40 million pesos, worth about $3 million then.

The government is now asking for a new remediation plan that not only targets soil contamination, but other components such as water and air. Albores did not say how much this could cost the company.

Grupo Mexico did not immediately reply to a request for comment on the causes of the spill and the government complaint.

The miner said in an Oct. 4 statement that remediation work in the river was successful and backed by scientific studies.

Shares in Grupo Mexico were down 2.3% after Albores' comments on Thursday.

($1 = 17.8868 Mexican pesos)

(Reporting by Ana Isabel Martinez and Valentine Hilaire; Editing by Brendan O'Boyle and Marguerita Choy)