UEFA has opened an investigation into a possible breach of disciplinary regulations by several Real Madrid players at the end of their recent Champions League match at Atletico Madrid, European soccer's governing body said on Thursday.

The inquiry centers on allegations of improper conduct by Antonio Ruediger, Kylian Mbappe, Dani Ceballos and Vinicius Jr, UEFA said.

Real progressed to the Champions League quarterfinals on March 12 after a penalty shootout and celebrated in front of the crowd.

While UEFA did not detail the incidents under review, Spanish media reported that Atletico filed a complaint over the behavior of Real's players during their celebrations.

Video footage showed several Real players dancing and making gestures towards the Atletico supporters, who responded by throwing objects from the stands.

Reuters has contacted Real for comment.

UEFA said it would provide more information in due course.