Tan, 51, was ordered to be released by Singapore's Court of Appeal on Wednesday after judges said the grounds for his detention set out few connections with Singapore.
He had been in custody since October 2013 under a law that allows Singapore's Ministry of Home Affairs to detain without trial up to a year a person who has been associated with activities of a criminal nature if the ministry deems it necessary in the interests of public safety, peace and good order.
"FIFA is very disappointed with the Singaporean Court of Appeal’s decision to release Mr Tan given the gravity of his past activities relating to match manipulation," said football's governing body in a statement sent to Reuters.
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"The integrity of the game is a top priority for FIFA and we continue to work closely with law enforcement agencies as well as the respective public authorities and other sports organisations on a national, regional and global level to tackle the issue of match manipulation."
"Match manipulation is a threat that undermines the integrity and credibility of football at different levels of the game. FIFA has a zero-tolerance policy on match manipulation and is committed to protecting the integrity of football by all means necessary."
Interpol lauded Singaporean authorities when they arrested the businessman in 2013, saying he was the "mastermind" of the world's largest and most aggressive football match-fixing syndicate.
In the written decision, the judges described Tan's acts as "reprehensible" but said "there is nothing to suggest whether (or how) these activities could be thought to have a bearing on the public safety, peace and good order within Singapore."
Tan still faces charges in Italy and Hungary, Singapore's Straits Times reported.
(Writing by Brian Homewood in Berne; Editing by Amlan Chakraborty)
