The Swansea players Lee Trundle and Alan Tate will be interviewed by police this week and could face prosecution and suspension following their post-match celebrations at the Millennium Stadium.
Swansea beat Carlisle 2-1 in Sunday's Football League Trophy final, Trundle scoring the opening goal, but afterwards he carried a Welsh flag bearing the words "Fuck off, Cardiff' and put on a T-shirt on which a cartoon showed a man urinating on a Cardiff No 9 shirt. Both the flag and T-shirt are believed to have been thrown to him by Swansea fans.
South Wales Police have launched an investigation and Chief Superintendent Bob Evans said: "We've had a number of complaints - many from Swansea fans, it must be said - and are therefore obliged to launch a full investigation into the matter.
"We take a very dim of this matter because there were a lot of families and young children at the game and it is noticeable that many Swansea fans have themselves come to us to make a complaint - it has not been only Cardiff fans."
Any charges would relate to public order offences while the Football Association of Wales is also set to discipline the players with a disrepute charge.