The clubs include some famous names in European football including Atletico Madrid, Sporting Lisbon, Fenerbahce and Malaga, but no British sides.
The sanctions follow the first elements of UEFA's financial fair play rules coming into force regarding unpaid debts, with the prize money temporarily withheld pending further investigation.
The action was taken by the UEFA Club Financial Control Body (CFCB) investigatory chamber, chaired by former Belgian Prime Minister Jean-Luc Dehaene.
UEFA said in a statement: "The clubs participating in UEFA club competitions had to provide information regarding the status of any overdue payables as at 30 June 2012.
"The CFCB investigatory chamber has identified that important overdue payables towards other clubs, and/or towards employees or social/tax authorities existed in 23 cases."
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