The five Mexican footballers who were suspended from the Gold Cup last week, are not the only players to have tested positive for the banned substance clenbuterol, according to FIFA president Sepp Blatter. The players claim that the positive test was caused by contaminated meat and Blatter appears to hold the view that they ingested the drug by accident. \"It was obviously a surprise but when we received the documents, and especially after we had spoken to our medical supervisor, we noticed that there were five players in an awkward position,\" Blatter told ESPN. \"But traces of the product have also shown up in the systems of some of the other players in the team. \"It is without doubt in the food and we are talking here, about meat. The Mexican football federation is going to take all necessary measures and we (FIFA) are ready to lend a hand.\" The World Anti-Doping Agency (WADA) said on its website that it had been in touch with the Mexican authorities about the possibility of contaminated meat, adding that its experts would examine the case. The five players whyo tested positive were Guillermo Ochoa, who plays for Mexican side America, Francisco Javier Rodriguez of Dutch side PSV, Edgar Duenas of Mexico\'s Toluca, Antonio Naelson of Toluca and Christian Bermudez of Atlante. They failed their tests on May 21 before the start of the Gold Cup. The results were made known after their opening game at which point they were replaced. Their teammates have gone on without them to reach Sunday\'s final where they will meet the USA. Last week WADA science director Olivier Rabin said they may consider changing the rules on clenbuterol. Spanish cyclist Alberto Contador still remains under investigation for a similar positive dope test during last year\'s Tour de France, with contaminated meat again blamed for the presence of clenbuterol.