Administrators have been appointed after former Socceroos captain Lucas Neill was declared bankrupt in the UK.

Neill, who is believed to have earned about $40 million playing in England for 15 years, was declared bankrupt in January.

London-based Insolvency experts Begbies Traynor were appointed trustees to the bankruptcy last week.

"Mr Neill is due to be interviewed when he returns to the UK in the coming weeks," Dale Hernon of Begbies Traynor said in a statement.

"At which point the trustees will be able to obtain the background information required to determine the full scale of Mr Neill's debts. At this early stage of proceedings, it is currently unclear to what extent any funds will be recovered."

Neill is believed to have invested in property in both Australia and the United States.

The 38-year-old from Sydney played for Australia on 96 occasions before being left out of the Socceroos' 2014 World Cup squad.

Neill's English club career began with Millwall in 1995. He also played with Blackburn Rovers, West Ham United, Everton and most recently Watford.

He has also had stints in the Middle East, Turkey and Japan as well as playing four A-League games for Sydney FC in 2013.