Breno detained following house fire
It said the 21-year-old player was detained for "fear of flight and danger of suppression of evidence."
Breno, who was briefly admitted to hospital for smoke inhalation on Tuesday after his villa was gutted by a late-night blaze, had been under investigation since Friday when forensic officers ruled out the fire being an accident.
The club confirmed on Friday that the player was formally under investigation but could not be reached for comment on the latest twist in this case as the team prepared to play Bayer Leverkusen later on Saturday.
Brazilian Breno, who is recovering from an injury, was alone at home at the time of the fire which gutted the house in Munich's Gruenwald neighbourhood.
Dozens of fire fighters were called in to put out the fire before it threatened nearby houses.
The club found a new home for the player, his wife and three children and the family moved in on Thursday.
Breno joined Bayern as an 18-year-old in 2008.