Southampton have said they will ban any supporters found to have made indecent gestures towards Cardiff fans mocking the death of Emiliano Sala during Saturday's Premier League match at St Mary's Stadium.
Cardiff were in action for the first time since the striker's body had been recovered from underwater wreckage in the English Channel and formally identified by the Dorset coroner.
The flight carrying Sala from Nantes to Cardiff following his £15million transfer to the Premier League club crashed into the sea near Alderney on January 21. Pilot David Ibbotson remains missing.
A minute's silence had been impeccably observed as part of the tributes before kick-off at the game, which the Welsh side went on to win 2-1 with Kenneth Zohore's dramatic goal in the third minute of stoppage time.
However, video later emerged on social media of two men in the home section of the stadium apparently making aeroplane gestures in the direction of the away fans.
Southampton confirmed both supporters had been spoken to by Hampshire Police and intended to take "an extremely firm stance" over the incident.