Manchester United manager Jose Mourinho has been accused of using a trust fund located in New Zealand in the name of his wife to avoid paying tax.
European publications first accused Mourinho of moving millions of pounds offshore, including to a trust names Kaitaia Trust located in Auckland, to minimise his tax bill on December 3.
Mourinho has strongly denied any wrongdoing.
The investigation dubbed Football Leaks is based on millions of leaked documents and was conducted by the European Investigative Collaborations consortium. It claims to have found evidence suggesting that tax officials in Britain and Spain had been misled by Mourinho's advisers when he was manager of Real Madrid in Spain from 2010 to 2013. Top football players Cristiano Ronaldo and Mesut Ozil were also named in the documents.
During Mourinho's Real Madrid period he did not originally pay tax on his image rights earnings to the Spanish tax authorities.
They opened an investigation into this in 2014 and on July 3, 2015 Mourinho was issued with a tax bill for €2.1 million ($3.1m) for the period 2010-2013 for that unpaid tax on image rights earnings of just under €12m ($17.7m).
According to the latest Football Leaks allegations he was able to reduce that tax bill by filing company expenses.
The investigation's revelations suggest Mourinho's image rights were ceded from a company owned by him called Koper, located in the British Virgin Islands, to two companies in Ireland.
Koper was in turn controlled by Kaitaia Trust, formed in Auckland in 2008. The investigation allegedly found the beneficiaries of the trust were listed as "Mourinho's current wife and his children".
Another document is said to state that, as of December 31, 2013, Kaitaia owed Mourinho nearly £10m ($17.6m).
However, Mourinho's agent Gestifute denied any wrongdoing on his part and said Mourinho paid more than €26m ($40.6m) in taxes when he lived in Spain from 2010-13.
Gestifute, which also has Ronaldo as a client, published documents allegedly showing that Spanish fiscal authorities have certified that Mourinho and Real Madrid star Ronaldo are "up to date on ... obligations."
Mourinho coached Real Madrid from 2010-13 and took charge of United this season.