Swiss banks have noted 53 possible money-laundering incidents in the investigation of FIFA's 2018 and 2022 World Cup bidding contests, the country's attorney-general said on Wednesday.

Michael Lauber said the "suspicious bank relations" were reported within the framework of Switzerland's anti-money-laundering regulations.

Lauber said he does not exclude interviewing FIFA President Sepp Blatter and Secretary-General Jerome Valcke in the future, although neither is currently under suspicion.