The drug has been unidentified while the club has suspended the player from all matches "pending the outcome of the legal process".
Man City's Toure suspended after testing positive
MANCHESTER // The defender Kolo Toure has been suspended after failing a doping test.
Manchester City issued a statement saying "the FA has informed Kolo Toure that an 'A-sample' provided by him has tested positive for a specified substance."
The club added that Toure has been suspended from all matches "pending the outcome of the legal process," and that it would not provide any further comment.
The World Anti-Doping Agency define a specified substance as one that is "more susceptible to a credible, non-doping explanation," and its punishment for such a positive test ranges from a warning to a two-year ban.
The 29-year-old Toure joined City for £14million (Dh80m) from Arsenal in 2009. He was City's club captain under former manager Mark Hughes but was succeeded by Carlos Tevez for this season.
His brother Yaya Toure also plays for City.
Meanwhile Arsene Wenger, the Arsenal coach, has come to the defence of his former captain. Wenger says he has spoken to Kolo who blames it on a diet supplement belonging to the player's wife.
Wenger said Toure "wants to control his weight a little bit because that's where he has some problems. He took the product of his wife."
The French coach said the Ivory Coast player was "a boy who has a clean life, very honest living, always at home, a family man" and was simply "not cautious enough."