The ex-midfielder, who starred in the Whites team that reached the semi-finals of the Champions League in 2001, was officially declared bankrupt on July 28 but details are still emerging.
Insolvency firm Begbies Traynor has taken up the case and says the “full scale of the debts” is uncertain.
Matteo, 41, admitted in his 2011 autobiography ‘In My Defence’ that he lost more than £1million gambling on horses, once losing £100,000 on a single horse.
Matteo’s 17-year professional career ended in 2009 after a two-year spell with Stoke City. He also played for Liverpool and Blackburn Rovers, and won six caps for Scotland.
Towards the end of his career, he took up racehorse ownership. In recent years he has worked as a TV football pundit, newspaper columnist and as director of Rock Bar, in Call Lane, Leeds.
Dale Hernon, from Begbies Traynor, said: “It is very early in the process as the trustees have yet to obtain all the required background documents and interview Mr Matteo, so the full scale of the debts and the likelihood of any funds being recovered is uncertain.
“Mr Matteo was a highly respected footballer, especially in Leeds where he also had other business interests, and there has been a great deal of interest in the case.”
It is expected that the investigation into the father-of-two’s bankruptcy will take several months and Begbies Traynor has said creditors with claims will receive regular updates.
The former footballer declined to comment when contacted.