As things stand, Barca are unable to register Arda, who they signed from Atletico Madrid in the close season, until January because of a ban imposed on the club by FIFA for breaking rules on the transfer of minors.
However, a serious knee injury to Rafinha last month prompted Barca to ask the Spanish football federation (RFEF) and FIFA, football's world governing body, if they could replace the Brazil midfielder in the squad with Arda.
Barca were prevented from registering players for two transfer windows, with the ban officially expiring at the close of the last window.
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While they would normally have to wait for the new window to open in January, rules stipulate that in emergency cases such as injury, players can be registered outside the scheduled transfer windows.
"The legal department has confirmed that FIFA has not responded to the latest request presented on Friday, the third the club made," Barca said on their website (www.fcbarcelona.es) after a board meeting on Wednesday.
"Given the lack of a reply, an appeal will be presented tomorrow Thursday to FIFA's appeals committee as a precursor to an appeal to CAS," they added.
Lausanne, Switzerland-based CAS attempts to resolve sporting disputes through arbitration and its rulings carry the same weight as judgments by ordinary courts.
Barca are suffering something of an injury crisis, with Argentina forward Lionel Messi and Spain playmaker Andres Iniesta also sidelined.
Their next outing is a La Liga game at home to Rayo Vallecano on Saturday before they play at BATE Borisov in Champions League Group E on Tuesday.
(Reporting by Iain Rogers, editing by Toby Davis)
