Premier League club Chelsea have been banned from signing new players in the next two transfer windows as punishment for breaking rules on registering under-age players, FIFA said on Friday.
It means the club will be unable to make signings until the end of January next year.
"The Disciplinary Committee sanctioned Chelsea with a ban on registering new players at both national and international level for the next two complete and consecutive registration periods," FIFA said in a statement.
In addition, Chelsea were fined 600,000 Swiss francs ($600,000, 530,000 euros) and given a period of 90 days to regularise the situation of the minor players concerned.
The ban does not prevent players being released by the club and it does not apply to Chelsea's women's and futsal teams.
Chelsea have been given three days to appeal against FIFA's decision.
The move follows a FIFA rule into Chelsea's signing of foreign under-18 players, including the club's former forward Bertrand Traore, a Burkina Faso international who now plays for French Ligue 1 club Lyon.
Traore signed professional forms for Chelsea in 2013 at the age of 18 but was not registered until January the following year.
French website Mediapart, quoting documents from Football Leaks, reported that FIFA had scrutinised 19 Chelsea signings.
Mediapart reported that FIFA found evidence that Chelsea had supplied misleading information about Traore's signing and that he had made more than 20 appearances for the club at different age levels despite not being registered by the Football Association.
FIFA said on Friday it was also fining the Football Association 510,000 Swiss francs for breaking the rules on signing minors.
The world governing body gave the FA a period of six months to update its processes concerning international transfers and the registration of minors.