Fifty Swiss bank accounts allegedly linked to world football governing body Fifa have been frozen.
US officials believe "corruption money" may have been moved through the now frozen accounts, the Swiss justice ministry said.
Between 50m and 100m Swiss francs ($50.1m-100.2m; £34m-£67m) was in them, media reports say.
An earlier version of this story incorrectly stated the accounts belonged to Fifa.
Meanwhile, suspended Fifa President Sepp Blatter has been appearing before the organisation's ethics committee.
Mr Blatter, who is due to depart from Fifa on 26 February, strongly pleaded his innocence over corruption allegations, his lawyer said.