Atletico Madrid have reportedly requested that Antoine Griezmann's deal to Barcelona be cancelled.
After paying the attacker's £108m release clause, Barcelona last week confirmed their new buy.
But the deal is not done and dusted yet as Atletico are requesting more money from the Spanish champions.
La Liga president Javier Tebas confirmed that Atletico have written to the body requesting that Griezmann's registration with Barcelona be blocked.
"Atletico wrote to us and placed in doubt whether or not we should grant Griezmann's licence at Barcelona," Tebas told Onda Cero.
"There is a mechanism that has been put in place and it will be the organisations that must resolve the situation. We don't have the element of judgement."
Griezmann has already made his debut for Barca against Chelsea in the International Champions Cup on Tuesday.
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