Mexican authorities have quarantined 1,800 cows in the city of Guadalajara, Mexico, following suspicions that they were contaminated with banned feeding chemical clenbuterol.

"We have immovilised 1,800 cows and detained three people," a spokesman for Agriculture agency Sagarpa told just-food. "We are stepping up surveillance in the province and across borders to ensure contamined meat does not reach consumers."

The cows, which came from the Arrayana ranch in the Ameca municipality, will be retained for 90 days, the spokesman added. Ranch owners were fined an undisclosed sum.

The measure follows the intoxication of an unstated number of people in Guadalajara, the capital of the Eastern Mexican province of Jalisco, which has 4m inhabitants.

The officials said Sagarpa has recalled tonnes of contamined beef in Guadalajara and alerted the population to buy beef from official supermarkets and stay away from street selling stands.

The spokesman denied reports that clenbuterol-laced meat is entering Jalisco from the Aguascalientes, Michoacan, Nayarit, Veracruz and Zacatecas provinces, adding that the situation is now under control in Guadalajara.