Zurich: Swiss banks have identified 53 instances of suspicious activity around FIFA's accounts for possible money laundering, Swiss attorney general Michael Lauber revealed on Wednesday.
Lauber said his office has seized "huge amount" of data for corruption inquiry from world football's governing body and it is being analysed.
The inquiry is part of a Swiss investigation regarding bribed bidding process for the 2018 and 2022 World Cups, awarded to Russia and Qatar, respectively.
Both countries have repeatedly denied any wrongdoing.
Lauber said the investigation focussed on 53 banking relationships reported by the Swiss financial intelligence unit.
"We are facing a complex investigation with many international implications," he was quoted as saying by bbc.com on Wednesday.
"The prosecution is ongoing and will take time. The world of football needs to be patient -- by its nature, this investigation will take more than the legendary '90 minutes'."
Lauber said the investigation would take a long time and that violation of anti-money-laundering was deep rooted.
"So far, our investigative team obtained evidence concerning 104 banking relations (relationships between banks and clients). And, be aware that every banking relation represents several bank accounts," he said.
"We note positively that banks in Switzerland did fulfil their duties to file suspicious activity reports. Partly in addition to the 104 banking relations already known to the authorities, banks announced 53 suspicious banking relations via the anti-money-laundering framework of Switzerland."
FIFA is facing its worst crisis with widespread corruption claims damaging its image following the arrest of seven of its top officials and indictment of 14 people by the United States.
The US Federal Bureau of Investigation (FBI) is in the midst of a major investigation into a massive corruption scandal dating back to the 1990s.