Real Madrid have released video footage appearing to show Barcelona midfielder Sergio Busquets calling Marcelo a "monkey".
The club released footage on their in-house TV channel with Busquets captioned as shouting 'mono, mono' at Marcelo during Barca's 2-0 Champions League victory at the Bernabeu last week.
Madrid, who had earlier released a video claiming to show Pepe made no contact with Dani Alves during the red-card incident, also provided video analysis of referee Frank De Bleeckere, who will take charge of Tuesday's semi-final second leg at Barcelona.
The video highlights the fact that De Bleeckere sent off Inter's Thiago Motta in controversial circumstances when they took on Barcelona at the Camp Nou during last season's semi-final, and calls on the official to avoid "falling for Barcelona's theatre".
Madrid had earlier requested that UEFA take action against Barca for 'premeditated anti-sporting behaviour' after they were deemed to have acted theatrically in the first leg, but the governing body has dismissed the case. The club had sought two-game bans for Busquets, Dani Alves and Pedro and one-game bans for Seydou Keita, Victor Valdes and Javier Mascherano, while Pep Guardiola was also accused of unsportsmanlike behaviour.
UEFA has also rejected Madrid's appeal over Pepe's red card and Barcelona's complaints over Jose Mourinho's post-match comments.
A statement on Monday afternoon read: "UEFA has announced today that the vice-chairman of the UEFA Control and Disciplinary Body, as a judge sitting alone, has rejected both the protests lodged by Real Madrid CF and the complaint made by FC Barcelona following the UEFA Champions League semi-final first leg between the two clubs last Wednesday.
"The protests lodged by Madrid, against the behaviour of the Barcelona players during the match and against the red card shown to Pepe, are rejected. In the case of the behaviour of the Barcelona players, it was deemed that there was no common strategy to provoke, while in the case of Pepe, the referee's factual decision is upheld. As a result, Pepe is suspended for the second leg on Tuesday.
"The complaint lodged by Barcelona, against the comments made by Madrid coach José Mourinho to the press, was also rejected by the vice-chairman of the Control and Disciplinary Body. In this instance, Barcelona have been referred to the proceedings already brought against Mr Mourinho, which will be heard by the Control and Disciplinary Body on Friday 6 May. No new disciplinary proceedings are therefore to be opened against Mr Mourinho on the basis of the complaint lodged by Barcelona.
"Both the above decisions are open to appeal within three days of the dispatch of the contested decisions."
As the war of words continued, Barcelona midfielder Xavi has hit out at Real's recent conduct and their attempts to stop Barca's passing game at the Bernabeu.
Madrid deliberately let the grass grow long and opted to keep the pitch dry for those matches in order to stifle Barca's slick passing game, a tactic which has angered Xavi.
"I believe people like to see attractive football on a good playing surface, not long grass and hard pitches," he said. "It's deplorable that there are no regulations in place for the state of the pitches. In 2011, there are still no regulations and that's regrettable."
Despite his reservations about the Bernabeu pitch, Xavi hopes the talk will soon return to the football following the off-field controversies of the last week.
"I have the feeling that we are talking very little about football and that makes me sad," he said. "I love playing against Real Madrid and I love playing in these big games. They are very exciting challenges. It's satisfying to be in the semi-finals and a reason to be proud."
Barcelona won their first ever European Cup at Wembley in 1992 and Xavi hopes his side can repeat that triumph in London this season.
"I watched it at home because my parents didn't let me go to Wembley," he recalled. "It was a great day for the club and now we have a chance to go back there. We are up against an historical rival in Madrid and it would be very special to beat them, to go back there for another final."