Reports suggesting two Chelsea fans had been attacked in the Turkish capital surfaced on Tuesday, and the Premier League club announced on its official Twitter account that they know of the issue.
"The club is aware of two incidents involving fans in Istanbul last night (Tuesday) and is working with relevant agencies to best ensure safety of all," the post read.
"CFC fans in Istanbul are reminded it's not safe to use Metro to and from the stadium today. Special bus is recommended."
Chelsea also reminded fans to continue checking the club's account for any updates in the build-up to the game.
The last 16 first leg clash at the Turk Telekom Arena will see Jose Mourinho's side come up against club legend Didier Drogba, who scored the winning penalty in Chelsea's victory over Bayern Munich in the 2012 Champions League final.
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