Portugal goalkeeper Rui Patricio quit his club Sporting on Friday, blaming its president for "psychological violence" against players and inciting anger among the fans, who attacked a number of players and coaches at their training ground last month.
In a resignation letter published by several local media outlets, the Euro 2016 winner said he was entitled to termination pay after being "the target of psychological and physical violence, which constitutes just cause for me to be free of the contract with Sporting Clube de Portugal".
Sporting President Bruno de Carvalho, under pressure to quit and facing a members assembly vote on June 23 that is expected to depose him, was quick to label the resignation an attempt to blackmail the club and accused the international players' agent Jorge Mendes of engineering it.
De Carvalho claims that Mendes wants Patricio to join the British side Wolverhampton Wanderers.
"Jorge Mendes sought to take advantage of the situation, which is a crime," he told a news briefing. "Sporting cannot be subjected to fear, blackmail and threats".
Nobody was immediately available for comment at Mendes' agency Gestifute.
The club had a tumultuous season and ended up losing the Portuguese Cup final to underdogs Desportivo Aves on May 20, five days after around 50 hooded supporters burst into the club's training camp, injuring striker Bas Dost and vandalising the dressing-room.
In April, a spat between de Carvalho and the players over their performance in a Europa League match culminated in him threatening to suspend almost the entire first-team squad.
On May 16, police detained de Carvalho's right-hand man Andre Geraldes and three other people linked to the club on suspicion of corruption, including game-fixing mostly in handball matches but also in some football events, by allegedly bribing referees and players.
In his letter, which quoted various de Carvalho's text messages calling the players "spoilt children" Patricio said that de Carvalho "criticised me publicly, offended me, suspended me and sued me."
"On various occasions he incited the fans' anger against me and my teammates, knowing all too well that some of the fans, especially from the organized groups, react in a primal and irrational fashion to any statements uttered by the president."