Liverpool football supporters have been warned that wearing a fez in Istanbul next week may offend the locals.
The fez hat may cause offence to many Turks
Hundreds of fans have been seen wearing the traditional Turkish hat at matches since the club qualified for Wednesday's Champions League final.
University of Liverpool lecturer Dr Alan Greaves says the fez was banned by Ataturk, the founder of modern Turkey, in 1925 and is now a contentious issue.
A police spokesman urged fans to heed advice given by Turkish authorities.
The fez - a brimless, tassled cap, originally from Turkey - is known to many as being the permanent trade mark of the late comedian Tommy Cooper's act.
Dr Greaves, an expert in Turkish history and archaeology, said: "It might be seen as a rejection of the work of Ataturk, the founder of Turkish secular democracy.
"The fez became a symbol of the preceding Ottoman Empire which was thought to be traditionalist.
"People wearing a fez could be seen to be harking back to the Ottoman Empire.
"It might be seen as an offence to the majority of Turks.
'Novelty or antique'
"It's history but not ancient history, and I don't know how people would interpret it. Legally I wouldn't know what the position is.
"I have seen fezzes on sale in Turkey, but you don't see people wearing them in the streets.
"It's different when they are being sold as an antique or novelty as opposed to people wearing them at an emotionally-charged event like a football match - it might be misconstrued and there is a chance it might cause offence."
A spokesman for Merseyside Police said: "We would advise all Liverpool fans travelling to Istanbul to take notice of any advice given to them by the local authorities in Turkey."
The Foreign Office said they always advise people to respect local customs when travelling.
A spokesman said: "The fez is sometimes seen as a symbol of a bygone era before the modern republic Turkey was founded.
"As a result wearing one may cause offence to some. Our general advice is we recommend visitors be alert and sensitive to local customs when travelling."