Roberto Mancini signed two different contracts when he was appointed Manchester City manager in 2009 as part of a scheme to avoid financial scrutiny, according to recent information obtained by Der Spiegel.
Mancini supplemented his earnings by agreeing to a deal with an Abu Dhabi club run by Sheikh Mansour's holding company, Abu Dhabi United Group (ADUG), the German magazine says.
City allegedly paid Mancini £1.45 million a year - less than the £1.75 million that he earned officially as an "advisor" to Al Jazira Sports and Cultural Club.
"We have some payments that require to be made by Al Jazira," a City executive is quoted as saying in documents reviewed by Der Spiegel. "We will need to send monies to ADUG and ADUG will then pass on to Al Jazira with payment instruction."
The hidden payment to Mancini is the latest in a series of explosive revelations by the whistleblower platform Football Leaks over the past week. Der Spiegel, which claims to have pored over millions of documents from the Football Leaks founder, has since detailed the elaborate ways in which City avoided more serious penalties, including threatening legal action against UEFA.
City, who were fined €20 million (roughly £17.4 million) in 2014 for violating Financial Fair Play regulations, denied the allegations.
"The attempt to damage the club's reputation is organized and clear," a City spokesperson told Der Spiegel.
Mancini left City in 2013 after winning the Premier League on the last day of the 2011-12 season. He is now coach of the Italian national team.