* Reports say Atletico, Real facing FIFA sanction
* La Liga clubs deny breaking transfer rules (Recasts with Real statement)
MADRID, April 29 (Reuters) - Real Madrid and city rivals Atletico have dismissed reports in Spanish media of a possible FIFA ban from the next two transfer windows over breaches of rules on the signing of foreign Under-18 players.
FIFA had decided to sanction the pair after a similar investigation that last year led to a ban for La Liga rivals Barcelona, according to the reports, which did not identify their sources.
"Real Madrid reiterates that the club has always scrupulously adhered to FIFA regulations," Real said on their website (www.