Phaedra Almajid told The Associated Press on Monday that she wrote to FIFA prosecutor Michael Garcia about Eckert breaching her right to witness confidentiality. It was sent late Sunday to the email address at the Manhattan law firm where Garcia is a partner.
In the letter of complaint, which has been seen by the AP, she wrote that Eckert "falsely discredits me in order to support his indefensible conclusion that the December 2010 bidding was wholly acceptable."
Almajid's protest adds to a chaotic response since Thursday when FIFA released Eckert's summary of the Garcia investigation into corruption in the 2018 and 2022 World Cup bidding contests won by Russia and Qatar, respectively.
Both Russia and Qatar have always denied any wrong-doing.
Garcia himself said his was work was misrepresented by Eckert and appealed to FIFA. He is challenging the German judge's decision to close the case because "problematic" wrong-doing by candidates was "of limited scope" and did not justify reviewing the votes by FIFA's executive committee.
Almajid gave evidence to Garcia alleging wrong-doing by Qatar's bid when she was its head of international media until early 2010.
She said Eckert's report denounced her as unreliable in a "crude, cynical and fundamentally erroneous" summary of her co-operation.
"My co-operation was based on your promise of confidentiality," Almajid wrote to Garcia.
Though not named by Eckert in his 42-page document, Almajid was easily identified — in a section covering Qatar titled "Role and Relevance of a "Whistleblower" — from her previous public statements. She was named in a July 2011 statement in which she retracted her claims of corruption, but later said she was coerced to do so by Qatari bid officials.
Almajid's most serious allegation was aired by a British Parliamentary committee in May 2011, that African members of FIFA's ruling board were paid $1.5 million to vote for Qatar in a five-nation contest.
She also made allegations to Garcia of Qatar's $1.8 million sponsorship of an African football meeting in Angola in 2010, and how the Aspire Academy in Doha was used to further the emirate's campaign.
Still, Eckert wrote that Garcia's investigation report concluded that "it appeared that the (whistleblower) source has altered evidence to support its allegations."
Almajid said speaking out had jeopardized the safety of herself and her two sons.
"I have taken great personal risks to stand up for the truth in a highly politicized atmosphere," she wrote to Garcia. "However I have found myself betrayed and denigrated for being courageous enough to come forward with critical information."
Garcia must now decide whether to use Almajid's complaint to prosecute a case against his ethics committee co-chairman for unethical behaviour.
Eckert and Garcia are scheduled to meet this week for talks to resolve their rift. They should also co-operate on ongoing prosecutions against individual FIFA voters.