FIFA has banned Real Madrid and Atletico Madrid from registering players for the next two transfer windows.
The punishment has been handed out for breaches committed by both clubs that relate to the international transfer and registration of players under the age of 18.
"The two clubs were found to have violated several provisions concerning the international transfer and first registration of minor players as well as other relevant provisions with regard to the registration and participation of certain players in competitions," read a statement on FIFA's official website.
As this month's transfer window is already open for business, the Spanish capital-based pair will still be permitted to make additions to their squad if they opt to do so.
Instead, the suspension will come into force in the summer, which means that neither club will then be able to register any new signings until July 2017.
FIFA also confirmed that other teams can still sign players from either Real or Atletico during that period.
La Liga rivals Barcelona were dealt the same punishment in April 2014 for similar offences.
