Russia and Qatar have denied wrongdoing in the conduct of their bids for the 2018 and 2022 tournaments, which were not the subject of charges announced by U.S. prosecutors a week ago against FIFA officials that stunned world soccer.
FBI has been looking at the Qatar bid at least since September 2011. Investigators reportedly interviewed a former Qatar bid employee who said she was present when the Qatar bid organisation paid $1.5m to three African members of FIFA's executive committee to secure their votes for Qatar.
Amid the widening corruption scandal engulfing FIFA, Qatar has insisted there was "no way" it would be stripped of hosting the 2022 World Cup, because it had the best bid.
There was some surprise at the time that the tournament had been awarded to a small desert country with no real football tradition and where summer temperatures can top 40 degrees Celsius (104F).
Russia has also dismissed concerns it might lose the right to host the 2018 event.
"Cooperation with FIFA is going on and, most importantly, Russia is continuing preparations for the 2018 World Cup," Dmitry Peskov, President Vladimir Putin's spokesperson, said on Wednesday.
