The Football Association has charged Joey Barton for misconduct in relation to allegedly making 1,260 bets over a 10-year period, potentially scuppering his proposed return to Burnley.
The 34-year-old is alleged to have placed the bets between March 26, 2006, when he was still with Manchester City, and May 13, 2016, less than a week after he had helped Burnley win the Championship.
An FA statement read: "Joey Barton has been charged for misconduct in relation to betting.
"It is alleged that between 26 March 2006 and 13 May 2016, he placed 1,260 bets on the result, progress, conduct or any other aspect of, or occurrence in, football matches or competitions in breach of FA Rule E8.
"He has until 5 January 2017 to respond to the charge."
Only last month Barton was handed a one-match suspension by the Scottish Football Association from his short time with Rangers when he was found to have placed 44 bets between July 1, when his Gers contract started, until September 15.
The midfielder had already seen his contract with Rangers terminated by that point and his ban, which remains unserved, will be enforced at his next club should the SFA extend the request to FIFA to ensure it is applied worldwide.
Earlier this week Burnley announced they had agreed terms with Barton for him to return in January on a deal to run until the end of the season, but news of Friday's FA charge may now kibosh the arrangement.
The FA has been investigating Barton for the past few months, having been made aware of the potential breaches of its rules on betting, and that the sheer number of alleged bets involved over the past decade had led to a lengthy probe.
The timing of the charge, just three days on from Barton's potential reunion with Burnley being announced, is therefore understood to not be related to his latest career move as the FA was already in the process of finalising the charge.
The Clarets released a short statement on Friday that acknowledged the charge and stated they would review the situation with Barton and his representatives.
"Burnley Football Club have today been made aware of FA charges brought against Joey Barton relating to historic betting on football matches," it read.
"The club will be discussing the matter with Joey and his legal representatives and will be making no further comment on the matter at this time."
Those comments, and news of the charge, came after Burnley boss Sean Dyche had delivered his pre-Middlesbrough press conference on Friday afternoon.
When he had been asked about Barton, Dyche did not discuss the proposed deal in any great depth, only saying: "He's not a contracted player at Burnley Football Club.
"We've just had a chat with him and agreed in principle the idea of it going forward."