MEXICO CITY (Reuters) -- Mexico are seeking exoneration for five players suspended for doping in their CONCACAF Gold Cup squad, claiming they were victims of food contamination.

Goalkeeper Guillermo Ochoa, defenders Francisco Rodriguez and Edgar Duenas and midfielders Sinha and Christian Bermudez tested positive for banned anabolic agent clenbuterol and were suspended from the regional tournament.

The Mexican Football Federation (Femexfut) has already attributed the positive results to ingestion of clenbuterol in meat eaten by the players when on a training camp in Mexico to prepare for the Gold Cup.

"We are upset and we're seeking a pardon because (the players) are not to blame at all," Mexican Football Federation president Justino Compean told ESPN in an interview.

"We're doing all we can to get them exonerated. The sanction could be (suspension) from six months to two years but right now I'm not bothered about that, I'm concerned with getting (them) a pardon."

The five players were at a certified laboratory at UCLA in Los Angeles on Friday seeking new tests that could help exonerate them.

Clenbuterol can be used to speed up and increase muscle mass in animals.

"I'd like to talk of contamination and not doping, that's the truth. We can't say the players are doped, I insist, they're contaminated because anybody, including the coaching staff, may be contaminated but they weren't dope tested," Compean said.

Gold Cup organisers were investigating the case, including making a decision on whether to allow Mexico to call up five replacements.

"I'm sure they will say yes, I'm very confident," Compean said.

In Mexico, farming officials were checking beef supplies at the national team's High Performance Centre.

Title holders Mexico are the first team to have qualified for the quarter-finals after two 5-0 wins in Group A, against El Salvador on Sunday and Cuba on Thursday. Ochoa and Rodriguez were in the team on Sunday.

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