Cardiff City have contacted South Wales Police over the controversial 'swim away' gestures performed by Swansea manager Russell Martin and goal-scorer Jamie Paterson during Sunday's derby.
The Bluebirds say they have "issues of concern" around a number of incidents in Swansea, with directors Ken Choo and Steve Borley allegedly abused.
Cardiff have also been in touch with Swansea and the EFL.
"We can confirm that we are in dialogue with Swansea City, South Wales Police and the EFL over a number of issues of concern," a Cardiff City spokesperson told the BBC.
The 'swim away' gesture references a violent clash between rival supporters following a derby encounter in the 1980s.
The Bluebirds are also angry TV images of manager Mick McCarthy, shortly followed by chief executive Ken Choo and director Steve Borley were broadcast on the big screen at Swansea.com Stadium.
It is believed those images led to Choo and Borley being verbally abused by home fans.
EFL rules say images of "the area of the trainers' bench" should not be shown on big screens but there are no regulations regarding directors' boxes.
A Swans statement read: "Swansea City can confirm that the club is in dialogue with Cardiff City, South Wales Police and the EFL over events that took place during and after Sunday's game at the Swansea.com Stadium.
"Discussions will also take place within the club across all departments as a matter of process, as they do after every event that we host."
The FA are understood to be looking into the 'swim away' gestures.