ZURICH -- Former FIFA anti-corruption adviser Mark Pieth says Sepp Blatter should face a criminal investigation for selling under-valued World Cup television rights to Jack Warner.
Pieth, a Swiss professor of criminal law, said: "Blatter has to defend himself against a form of embezzlement charges."
Swiss broadcaster SRF has published a Blatter-signed FIFA contract from 2005 that gives the Warner-controlled Caribbean Football Union rights to the 2010 and 2014 World Cups for $600,000.
Warner reportedly sold the rights through a family company for around $20 million.
Now indicted in a U.S. probe of football corruption, Warner previously claimed he secured cheap World Cup rights for helping Blatter win presidential elections.
Pieth sais: "They have prima facie evidence. That means they have to open an investigation."
U.S. attorney general Loretta Lynch, meanwhile, said in her address to the IAP conference that no individual was immune from prosecution and that the cooperation with the Swiss authorities had been crucial.
She said: "Our message is clear: no individual is impervious to the law. No corrupt organisation is beyond its reach.
"It is this spirit of cooperation that allowed both Switzerland and the United States to announce this past May that we are conducting investigations into bribery and corruption in the world of organised football.
"In the United States, that investigation resulted in charges including racketeering, wire fraud and money laundering conspiracies spanning two decades. It exposed high-ranking officials of FIFA; leaders of regional and other governing bodies under the FIFA umbrella; and sports marketing executives who, according to the indictment, paid millions of dollars in bribes and kickbacks to obtain lucrative media and marketing rights to international soccer tournaments.
"It resulted in arrests here in Switzerland through the assistance of Attorney General [Michael] Lauber, Swiss authorities and their colleagues in the Federal Office of Justice, and is continuing with an independent Swiss investigation of FIFA."
Information from the Press Association was used in this report.