Dundee United have told fans they have a “zero tolerance policy” towards pyrotechnics in the wake of a smoke bomb being set off at the home match against Celtic.
Tangerine-coloured smoke billowed out of the lower tier of the Eddie Thompson Stand before kick-off on Friday night.
A club statement said: “Dundee United would like to remind supporters about a zero tolerance policy with regard to the use and carrying of pyrotechnics.
“The use of pyrotechnics, including smoke bombs and flares, within football stadiums is extremely dangerous and a serious offence.
“Any supporter identified to have committed such an act will be banned by the club and also subject to the possibility of criminal prosecution.
“Dundee United Football Club will work closely with the police, security and football authorities to eradicate this, and other, types of spectator misconduct.
“We would also like to remind supporters that if there are incidents of this nature in the future the football authorities have the power to impose serious sanctions including financial penalty and order matches to be played behind closed doors.
“The club urges all supporters to assist us in this matter and help end this unacceptable behaviour.
Thank you for your continued support.”