MEXICO CITY (Reuters) -Mexico's antitrust watchdog Cofece said it could fine Walmart (NYSE: WMT )'s local unit Walmex up to 8% of its income if it does not comply with a resolution prohibiting the retailer from engaging in certain conduct deemed illegal, the regulator said on Monday.

Cofece's statement comes after Walmex reported on Friday that Cofece ordered the company to pay a fine of over 93 million pesos ($4.62 million) for engaging in a monopolistic practice involving its suppliers.

"For 13 years, Walmart used its market power to impose abusive conditions on its suppliers, obtaining illegal advantages over its competitors," the watchdog said in the statement, outlining several prohibitions it levied on Walmex, Mexico's largest private retailer.

Walmex did not immediately respond to a request for comment on Cofece's statement, but said on Dec. 13 that it believes the regulator's analysis is incorrect and that it will appeal its ruling.

Cofece on Monday said it had prohibited Walmex from taking reprisals against suppliers in the form of sanctions or terminated contracts in retaliation for the supplier's commercial relations with other self-serve stores.

The antitrust body said it also prohibited Walmex from demanding or imposing prices on its suppliers and from requiring its suppliers to provide information on the prices or conditions they offer to other businesses.

"Cofece will verify compliance with the measures for ten years and may fine Walmart up to 8% of its income if it does not comply with this resolution," the regulator said.

($1 = 20.1190 Mexican pesos)