Uefa have suspended Besiktas from European competitions for one year and fined them €200,000 due to financial problems at the Istanbul club, Turkish media reported today.
The move came after Uefa scrutinised Besiktas' accounts in the second and third quarters of 2011 and ruled that they breached articles of the ruling body's financial fair play regulations.
Shares in Besiktas tumbled more than 9 percent on the news to 4.29 lira.
Besiktas Chairman Fikret Orman and the club's lawyers attended a meeting with Uefa's disciplinary committee for a second time on Wednesday after the club was earlier warned about its financial status and high debt.
Orman said Besiktas would appeal to the Court of Arbitration for Sport (CAS) regarding the ban, but added he was not very optimistic about a ruling in favour of the 13-times Turkish champions.
"We will defend the club's rights until the end, and will appeal to CAS as the first step," Levent Erdogan, a lawyer and club board member told Turkey's Dogan news agency.
"I think it's a dramatic decision, and it will hit us pretty badly, but there's nothing we can do," he added.