Spain's LaLiga on Monday filed an appeal and requested precautionary measures against the ruling issued by the Spanish sports council (CSD) authorising Barcelona players Dani Olmo and Pau Victor to play until the end of the season.
LaLiga issued a statement calling for "an urgent judicial response" in the name of sporting fairness, claiming that the CSD's resolution "violates" the rules governing the economic control of the Spanish league.
The CSD, which is responsible for settling the dispute between Barca and LaLiga, ruled in favour of the Catalan club on 3 April.
It said the cancellation of the registrations was "null and void", allowing midfielder Olmo, who joined Barca from RB Leipzig last summer, and young striker Victor to play.
LaLiga immediately contested this decision, saying it was "not in accordance with the law".
According to the governing body, the licences of the players, who were temporarily registered at the start of the season following the injury to defender Andreas Christensen, "automatically expired" on 31 December at a time when Barca were trying to find a new source of revenue to comply with financial fair play rules.
The Catalan club thought it had achieved this when in January it made official the sale of VIP boxes at the under-construction Camp Nou to Middle Eastern investors for an estimated €100 million over 20 years.
However, according to LaLiga: "No amount from the (VIP box deal) is ultimately recorded in the profit and loss accounts, contrary to what had been certified by the club and the auditor at the time of said transaction."
The CSD had given Olmo and Victor temporary permission to play for Barcelona again in January, pending a final decision.
Barcelona have been in financial difficulty for several years and in 2022 sold off various parts of the club and future television rights income to be able to sign stars including Robert Lewandowski and Raphinha.
Spending in the upcoming summer transfer window will be difficult for Barcelona without prior sales if LaLiga's new view of their financial situation remains the same.