MEXICO CITY (Reuters) - Mexico's antitrust watchdog Cofece ruled that Walmex, the local unit of U.S.-based retail giant Walmart , engaged in a monopolistic practice related to its suppliers, the company said in a statement on Friday.

Walmex noted it has been ordered to pay a fine of just over 93 million pesos, or about $4.6 million, while stressing it believes the regulator's analysis is incorrect and that it will appeal its ruling.

"Walmex is disappointed by this decision but will comply with Cofece's resolution while challenging the decision," the company said.

The Cofece resolution follows an investigation into Mexico's top retailer, which also operates stores in Central America, that lasted just over four years.

Cofece had accused Walmex of imposing prices and terms on its suppliers or distributors, in a case that centered on a lack of competition in the retail sector in many parts of Mexico.

In its statement, Walmex said the regulator acknowledged that the retailer can continue negotiating payments to its suppliers, except for two specific cases among the four originally investigated.

Walmex added that it does not believe the ruling will ultimately impact its operations.

($1 = 20.2422 Mexican pesos)