Real Madrid and Atletico Madrid have lost their appeals against transfer bans which were imposed on them for breaching rules on signing non-Spanish under-18 players, FIFA said on Thursday.

The decision by FIFA's Appeal Committee means that neither club can register players during the next two transfer windows and will have to wait until January 2018 to make any new signings.

The bans were initially imposed by FIFA's disciplinary committee in January, but were temporarily lifted pending appeals later the same month, allowing them to sign players in the transfer window which ended last month.

A statement said the Appeal Committee had decided to "confirm in their entirety the decisions rendered by the FIFA Disciplinary Committee in the respective cases relating to the protection of minors."

FIFA also maintained fines of 900,000 Swiss francs (£622,000) on Atletico Madrid and 360,000 francs (£249,000) on record 11-times European champions Real.

Both clubs, who have denied wrongdoing, have also been issued with a reprimand and a warning and given 90 days in which to regularise the situation of all minor players concerned.

Real and Atletico met in the final of this year's Champions League with Real winning on penalties after a 1-1 draw.

FIFA said that its rules, which ban international transfers of under-18 players except in certain circumstances, existed to "protect minors who move to other countries and prevent soccer clubs from exploiting them."

FIFA says that, in the past, trafficking of young players has left to some minors being virtually abandoned on the streets of foreign countries.

"Although FIFA's approach may appear harsh in an individual case, it is only by enforcing the rules consistently and strictly that the abuses of the past can be avoided and a proper and safe development of minor players secured," FIFA said.

FIFA received 2,716 applications for the transfer of minors in 2015, of which 393 were rejected, it said.