Newcastle midfielder Joey Barton will be allowed to leave the club on a free transfer, the club has announced.
Relations between Barton and the club have been strained after contract talks broke down, leading to the 28-year-old airing his frustrations on Twitter.
A club statement said: "The player has been advised that he can leave the club on a free transfer."
In response, Barton tweeted: "Somewhere in those high echelons of NUFC, they have decided, I am persona non grata."
Earlier on Monday, Barton, who has a year remaining on his contract at St James' Park, said on Twitter that he would make an announcement on his future at 4pm.
But before he could do so, the club made a statement on their website saying Barton had been placed on the transfer list and could leave the club immediately.
Barton added on Twitter: "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."
Newcastle had hoped to sell the 28-year-old, who joined the Magpies from Manchester City for £5.8m in 2007, this summer but a deal has not materialised.
After serving a six-month ban from football and a 77-day prison sentence for assault, Barton has rebuilt his career at St James' Park.
Though he clashed with manager Alan Shearer and was suspended in 2009, he resolved his differences with the club and played a key role in helping the Magpies gain promotion to the Premier League under Chris Hughton in 2010.
Last season, he scored four goals and set up nine more as Newcastle ensured their top flight survival by finishing 12th.
Talks of a new contract were put on hold when Andy Carroll left for Liverpool and stalled once more when his good friend and captain Kevin Nolan signed for West Ham, despite Barton saying he wanted to stay with club.