The 78-year-old Blatter, who is seeking a fifth term as president, said there are "no legal grounds to revoke the executive committee's decision (in 2010) on the award of the 2018 and 2022 World Cups."
But Blatter said FIFA can publish -- at least in part -- the 430-page investigation report into the bidding contest by ethics prosecutor Michael Garcia despite initially insisting it must remain confidential.
Last month, FIFA ethics judge Joachim Eckert released his 42-page summary of the report, essentially clearing Russia to host the 2018 World Cup and Qatar to host the 2022 tournament. But Garcia soon appealed to FIFA, saying his work was misrepresented by Eckert. The American lawyer then resigned on Wednesday after his appeal was rejected.
It wasn't immediately clear when publication will happen. In his summary last month, Eckert said whatever wrongdoing had occurred during the bidding contest in 2010 did not impair the integrity of voting by the FIFA executive committee.