Gareth Southgate is one of several former England players owed money by agent Terry Byrne, who invested the manager's cash without his permission as part of a disastrous £25million property deal.
Mail Sport can reveal Byrne also used money belonging to Joe Cole and Glenn Hoddle without telling them, as well as fees owed to Michelin-star chefs represented by his agency 10Ten Talent.
The purchase of giant new offices in central London last year has left some of Byrne's businesses facing the threat of liquidation amid significant debts to clients, with England boss Southgate, Cole and Hoddle owed huge sums.
Byrne remains on good terms with Southgate, but FA sources have told Mail Sport their professional relationship is likely to end due to the fallout from the missing money.
The boss appointed Byrne as his agent when he was Under 21s manager in 2016 and Byrne, 57, has since negotiated three new contracts with the FA on Southgate's behalf worth almost £20m, earning large commissions in the process.
Gareth Southgate had his own money put into a disastrous property deal without permission
Southgate's agent Terry Byrne (left) owes several former England internationals money
Southgate and the other former players have spent months trying to regain their money after 10Ten were late in making payments owed from sponsorship deals and commercial work.
The hugely experienced sports agent, who previously managed David Beckham and Pele, has admitted investing money without their consent and is seeking to repay them.
In a statement to Mail Sport, Byrne said: 'We are working with the talent regarding the repayments. The most important thing to me in all of this is that they are repaid fully.'
Byrne has enjoyed a successful 30-year career in football, representing some of the sport's biggest names, but this may now have been jeopardised by his ill-fated property deal.
His parent company Round World Group borrowed £21m from the Topland Group to buy a six-storey building near London's Oxford Circus last year, as well as taking out a £5m VAT loan.
Byrne had also lined up significant investment from fund managers Highams Saaz as part of an expansion - but the American firm withdrew, triggering a financial crisis.
Byrne (right) is a hugely experienced football agent who previously managed David Beckham
Round World Group, which includes 10Ten Talent, 10Ten Football and 10Ten Culinary, moved out of their new offices on Wigmore Street several months ago and the property is now in the hands of receivers.
Sources close to Byrne insist he was guilty of an error of judgment rather than deliberately deceitful, and several of the former players to whom he owes money are sympathetic to his plight.
Since the Round World Group was established as a talent management agency, focused mainly on football, in 2006 the company have expanded and moved into other sectors, branching out into media and chef representation, as well as setting up a film production company and a digital payment platform.
Byrne's financial problems could also have implications for the FA as another of his companies, 1966 Entertainment, have a long-standing contract to manage the commercial and charitable activities of senior England players including Harry Kane and Jordan Henderson.
The governing body also work closely with Byrne due to his relationship with Southgate, who features prominently in videos and photographs on the 10Ten website.
The FA have been seeking to reduce their links to Byrne for several years by bringing all of the players' commercial work under their control, but talks with 1966 over exiting a deal originally negotiated on the players' behalf by Beckham 17 years ago have proved difficult.
The FA served notice to 1966 of their intention to go it alone five years ago, but have yet to finalise the exit terms of a deal that runs until 2030.
As a result, the FA introduced a two-tier payment system in 2018, with players who received their first caps after that date including Declan Rice and Bukayo Saka paid directly by the FA and the likes of Kane, Henderson, Harry Maguire and Jordan Pickford still contracted to 1966.
Southgate features prominently in videos and photographs on the 10Ten website (pictured)
Until his recent problems, Byrne had enjoyed a hugely successful career in football, which began 30 years ago when he was hired as a part-time sports masseur by Chelsea.
He also worked there as first-team kit manager while training to be a physiotherapist.
While working at Stamford Bridge, Byrne developed a good relationship with Hoddle, who made him part of England's medical team when he was appointed national team manager after Euro 96.
Byrne became close to Beckham during his time in Hoddle's England set-up during the 1998 World Cup and later became his personal manager, moving to Spain to manage his affairs on a day-to-day basis after he signed for Real Madrid in 2003.
In addition to brokering his move to LA Galaxy in 2007, Byrne set up 1966 Entertainment with Beckham's then agent, Pop Idol creator Simon Fuller, and took complete control of the company after agreeing the commercial deal with the FA in 2009.
Following an amicable parting with Beckham - with whom he remains close friends - in 2010, Byrne founded 10Ten Talent, who have managed a host of top football stars including Pele, as well as branching out to launch 10Ten Culinary, who manage chefs.
Current 10Ten clients include Middlesbrough manager Michael Carrick, Southampton boss Russell Martin and former West Ham captain Mark Noble.
The FA and Southgate declined to comment.
Byrne told Mail Sport he is determined to make sure Southgate and Co are all fully repaid
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