Newcastle midfielder's rants on Twitter against his club - over his contract - are the final straw.
Joey Barton told he can leave
Newcastle United on Monday confirmed they have made Joey Barton available on a free transfer.
Relations between the club and the outspoken midfielder had already been strained following a breakdown of contract talks over the summer, with Barton taking to Twitter to air his frustrations.
The 28 year old did so again following Sunday's friendly defeat at Leeds United, before saying he would make an announcement on his future at 4pm on Monday UK time.
But the club pre-empted whatever Barton was going to say by announcing he is able to leave the club despite still have 12 months remaining on contract.
A brief statement on the club's official website read: "Newcastle United can today confirm that Joey Barton has been placed on the transfer list.
"The player has been advised that he can leave the club on a free transfer."
In response, Barton tweeted 55 minutes later than expected, getting in another dig at the board.
He wrote: "Somewhere in those high echelons of NUFC, they have decided, I am persona non grata.
"I am on a free but the honour of wearing those B+W stripes, surpasses that.
"One day the board might realise, what the shirt signifies. HONOUR and PRIDE. Thanks for your continued support........... #toonarmy."
Barton made reference to behind-the-scenes unrest on the social networking site on Sunday, following on from the full-back Jose Enrique who was recently fined by the club for accusing them of lacking ambition via his own account.
"If only we as players could tell the fans exactly how it is, without them above fining us lots of money. There will be a time and a place," Barton wrote. "If it wouldn't effect team morale and cause unrest within the dressing room, am certain Jose's comments would be the tip of the iceberg. ... And again it would be left to those magnificent fans to pick up the remnants of their once great football club. #hadenoughofcertainpeople.
"If I wanted to leave, I'd just come out and say I want to leave."
In May Barton's agent, Willie McKay, said the player would not be offered a new deal with the club.
The Liverpudlian has become a fans' favourite in the north east after initially suffering a troublesome start to his life on Tyneside.
After joining for £5.8million (Dh34.7m) from Manchester City in June 2007 he served a 77-day prison sentence after being found guilty of assault following an incident in Liverpool, while he was also given a suspended four-month sentence for a training ground assault on his then City teammate Ousmane Dabo.
The Dabo incident earned him a six-match ban upon his release from jail, before injury then curtailed his first team comeback, and his days at the club looked to be numbered as he was sent off in a late season clash at Liverpool, a game Newcastle lost 3-0 on their way to relegation from the Premier League.
He clashed with the then manager Alan Shearer in the aftermath and was suspended by the club, but resolved his differences sufficiently enough to remain with them in the Championship under the new manager, Chris Hughton and played key role in the Magpies' title-winning campaign.
He went on to become a key figure in the first team last season, and was understood to be close to extending his stay at St James' Park in January when the bombshell of Andy Carroll's departure to Liverpool dropped.
Talks were put on hold until the end of the season with the player later indicating that he would be happy to stay if his captain and friend, Kevin Nolan, also put pen to paper on a new deal.
But Nolan's exit to West Ham United last month was followed by the news that Barton would be leaving next summer, although recent developments have brought that forward.