Soccer: Uefa revealed the first sanctions under its financial fair play rules today, announcing it is withholding prize money for 23 clubs because of their failure to comply with the new rules.

The clubs, all participating in 2012/13 Uefa club competitions, were found to have overdue payments to other teams, their own employees or social/tax authorities and their payments would be withheld subject to further investigation, Uefa said in a statement.

Among the clubs under investigation are Atletico Madrid and Malaga of Spain, Portugal's Sporting, Dinamo Bucharest and Rapid Bucharest of Romania and Turkey's Fenerbahce.

Uefa approved the introduction of the far-reaching financial fair play rules in 2009 in a bid to reduce debt and introduce better and more transparent financial dealings among clubs playing in its competitions. Transfer fees and outgoing payments have been monitored since the start of the 2011/12 season with clubs tasked with breaking even in 2012 and 2013 and being assessed during the 2013/14 season.