Hein Verbruggen, former president of the international cycling union (UCI), offered his response Tuesday to accusations made by Armstrong in a British newspaper earlier this week.
"Since when do people believe Lance Armstrong?" Verbruggen wrote in a text message to the NOS television network in the Netherlands.
Cycling had reached a critical juncture in 1999, struggling to rebound from a widespread doping controversy.
That year, Armstrong tested positive for trace elements of a corticosteroid. Officials cleared the cyclist after his U.S. Postal Service team produced medical documents purporting that he had used a cream to treat saddle sores.
Armstrong is now saying that Verbruggen participated in the ruse, telling him "we've got to come up with something."
Verbruggen responded by questioning why anyone would believe the disgraced cyclist.
"Since he told Oprah Winfrey he had never 'sorted out' anything with the UCI?" Verbruggen wrote. "Or since he (for money!) makes films and gives interviews in which he apparently has to serve up juicy details?"
Armstrong has admitted to cheating throughout much of his historic career. He was issued a lifetime ban and stripped of his seven Tour de France victories and an Olympic medal.
Cycling officials are planning to convene an independent commission to dig into the sport's troubled past. Armstrong could be a key witness, but has hinted that he wants his punishment reduced in exchange for cooperating.