FIFA's chief ethics investigator says his assistant will lead the review of the Russian and American bids for the 2018 and 2022 World Cups to avoid any conflict of interest.
Michael Garcia, an American attorney, is investigating the bidding process for both World Cups and wants to speak to all bid teams - he is starting with representatives from England's 2018 World Cup bid this week and has warned that officials can face disciplinary measures if they refuse to co-operate.
Russia won the 2018 event and Qatar the 2022 tournament in a vote by FIFA's executive committee in 2010, but there have been allegations of misconduct - not least by England's former bid chairman Lord Triesman.
Garcia, however, is currently banned from entering Russia after his role in prosecuting a Russian arms dealer, and could have a conflict of interest in investigating the United States.
His office said in a statement: "The investigatory chamber continues to investigate the bidding process for the 2018 and 2022 FIFA World Cup events. Members of the investigatory chamber intend to speak with and request information from representatives of every bid team that vied to host the 2018 or 2022 FIFA World Cup.
"The fact that we request a meeting with members of a particular bid team does not mean that any specific allegation has been made by or against that team or anyone associated with it.
"The chairman of the investigatory chamber, Michael J Garcia, is leading the proceedings. However, in order to avoid the appearance of any conflict of interest, the independent deputy chairman, Cornel Borbely, is leading this effort with respect to the United States and Russia bids."
The statement says the review is only to investigate potential code of ethics violations, and not to "determine the venue or timing of the World Cup".
The statement adds: "We will consider any allegations and evidence indicative of such violations, and we urge anyone with potentially relevant information to contact us now.
"We emphasise that the FIFA code of ethics provides anonymity protections in appropriate circumstances.