MEXICO CITY (Reuters) -Mexico's antitrust watchdog Cofece ruled on Monday that corn flour and tortilla-maker Gruma can fix prices in the market, concluding following an investigation that competitive conditions in the key food segment do not exist.

Cofece said Gruma controlled between 50% and 90% of the market, adding in its ruling that it should break off some of its assets and halt various commercial strategies it employs.

Gruma said in a statement released after the decision that it has cooperated with Cofece's investigation, adding it has always operated lawfully.

It added that due to the preliminary nature of the ruling, it was not possible to predict how the antitrust body's governing body would ultimately resolve the case.

Cofece's investigation covered both the distribution and marketing of corn as well as the production, distribution and marketing of corn flour and related services, according to the watchdog's announcement published in the official government gazette.

"This market is fundamental for Mexico's economy and the wellbeing of consumers, especially due to its impact on the price of tortillas," the Cofece ruling said, referring to the country's staple food.

(Reporting by Raul Cortes; Editing by David Alire Garcia and Emelia Sithole-Matarise)