BERNE - The World Anti-Doping Agency (WADA) has accepted that five Mexican footballers who failed doping tests this year had ingested contaminated meat and should not be punished.

WADA said on Wednesday that after studying the case it had dropped an appeal to the Court of Arbitration for Sport (CAS) against the Mexico Football Federation (FMF) decision not to sanction the players.

It also issued a warning to athletes who compete in Mexico, venue for this month's Pan American Games.

"WADA has received compelling evidence from a FIFA study at the under-17 World Cup in Mexico that indicates a serious health problem in Mexico with regards to meat contaminated with clenbuterol," the anti-doping organisation said in a statement.

"This is a public health issue that is now being addressed urgently by the Mexican government.

"The government of Mexico, which has legislation forbidding the use of steroids with livestock, accepts it has an issue with contaminated meat and is actively looking to resolve the problem state by state," added WADA.

"Already several arrests have been made pursuant to these laws and large amounts of clenbuterol seized. Investigations are to continue.

"WADA applauds FIFA for the further research it has initiated while WADA, the Mexican Football Federation and the Mexican government have agreed to assist with the study which will continue as a joint project."

Gold Cup

Goalkeeper Guillermo Ochoa, defenders Francisco Rodriguez and Edgar Duenas and midfielders Antonio Naelson 'Sinha' and Christian Bermudez tested positive during the CONCACAF Gold Cup in May which Mexico went on to win.

The WADA decision was welcomed by FIFA.

"FIFA would like to express its satisfaction with the decision taken by WADA," said soccer's ruling body.

"This announcement by WADA confirms the initial decision taken by the Mexican Football Federation's disciplinary committee to clear the players of any wrongdoing which FIFA completely agreed with and supported."

WADA has issued recommendations to athletes who compete in Mexico.

"WADA's message to athletes travelling to Mexico remains the same and that is to exercise extreme caution with regards to what they eat and where they eat.

"If possible they should eat in cafeterias designated as safe by event organisers and also try to eat in large numbers.

"The state government in Guadalajara has taken steps to ensure the meat available to athletes at the Pan American Games will not be contaminated."