Cristiano Ronaldo's Saudi club Al-Nassr are banned from registering new players until unpaid debts are settled, Fifa said on Thursday.
The team "is currently prevented from registering new players due to outstanding debts", a Fifa spokesperson told AFP, without revealing the amount of the debts.
World football's governing body did not say whether Croatia midfielder Marcelo Brozovic's recent transfer from Inter Milan would be affected by the sanction.
"The relevant bans will be lifted immediately upon the settlement of the debts being confirmed by the creditors concerned," the spokesperson added.
In October 2021, Al-Nassr were ordered by a Fifa-appointed judge to pay Leicester City 460Â 000 euros ($514Â 000) plus interest in a dispute over the transfer of Nigeria international Ahmed Musa.
Musa joined Al-Nassr for 18 million euros in 2018. He left two years later and played for Turkey's Sivasspor last season.
According to the ruling at the time, in the event of non-payment Al-Nassr could be banned from recruiting players for up to "three entire and consecutive registration periods".
Backed by the Gulf state's sovereign wealth fund, the Saudi Pro League is luring big names from the major European leagues with the promise of huge salaries.
Former Liverpool captain Steven Gerrard took over as coach at Al-Ettifaq earlier this month, while Karim Benzema and N'Golo Kante have also made the move to the oil-rich Gulf state since Ronaldo's switch to Al-Nassr in January started the trend.