Zinedine Zidane
Zidane summer transfer plans may suffer a blow following Fifa banReuters

Real Madrid and Atletico Madrid have been banned by Fifa from all transfer activity in the next two transfer windows owing to irregularities regarding the signing of underage players. The Spanish giants will serve the sanction in the next summer window and the 2017 January mercato, as the ban does not affect the current registration period.

The ban is similar to the one handed down to Barcelona in April 2014 over the same wrongdoing. The Catalans had that embargo temporarily lifted following an appeal, allowing them to make numerous deals in the summer of that year for the likes of Luis Suarez, Ivan Rakitic, Jeremy Mathieu, Thomas Vermaelen and Marc-Andre ter Stegen.

The Champions League club winners were unable to register any new players during both the last January transfer window of 2015 and in the last summer mercato.

Real Madrid and Atletico are expected to follow the same procedure, appealing the ban to be able to sign next summer, meaning they would serve the embargo in January 2016 and the following summer.

Reports in Spain in 2014 suggested that the two Madrid-based teams were under investigation. Fifa have now confirmed the ban in an official statement.

According to Fifa's article 19, under-18 players can only move countries if their parents relocate to the vicinity of the buying club for reasons unrelated to football, if the transfer is within the EU and the player is between 16 and 18; and if the player's home is less than 50km from his country's border, and the parent association of the buying club is within a similar distance.

A statement from world football's governing body read: "The Fifa Disciplinary Committee has sanctioned Spanish clubs Atlético de Madrid and Real Madrid for breaches relating 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."

"Both clubs are to serve a transfer ban that prevents them from registering any players at national and international level for the next two complete and consecutive registration periods for breaching articles 5, 9, 19 and 19bis as well as annexes 2 and 3 of the Regulations on the Status and Transfer of Players (the "Regulations"). The transfer ban, which does not affect the current registration period at all, given that it opened before the decisions were notified, applies to each club as a whole – with the exception of the women's, futsal and beach soccer teams – and does not prevent the release of players."

"Additionally, Atlético de Madrid and Real Madrid have been fined CHF 900,000 and CHF 360,000 respectively, while both clubs have been issued with a reprimand and given 90 days in which to regularise the situation of all minor players concerned."