FIFA president Sepp Blatter has admitted that he is "surprised" by Michael Garcia's decision to resign as the governing body's lead ethics investigator.
The American lawyer stepped down from the role on Wednesday, claiming that the organisation suffers from a "lack of leadership".
Garcia was in charge of investigating corruption claims linked to Russia and Qatar's successful bids for the 2018 and 2022 World Cups, but he was unhappy with how his findings were presented by chairman of the Independent Ethics Committee Hans-Joachim Eckert.
"I am surprised by Mr Garcia's decision," Blatter is quoted as saying by BBC Sport. "The work of the Ethics Committee will nonetheless continue."
Blatter and other top FIFA officials are currently in Marrakesh for the Club World Cup.