Swiss Attorney General Michael Lauber told journalists Wednesday in the Swiss city of Bern that he did not exclude interviewing Blatter and Secretary-General Jerome Valcke as the investigation deepens.
Swiss authorities had previously said that Blatter, who has announced he will step down as president, was not part of the inquiry.
Lauber also warned that it was going to be a lengthy investigation and that Swiss law prevented him from revealing any detail about it despite what he acknowledged was "enormous public interest" in the case.
