Chelsea have made an official complaint to UEFA after investigating reports of their supporters being struck by baton-wielding stewards and police before and after last month's Champions League defeat at Barcelona.
Along with the Chelsea Supporters' Trust, Football Supporters' Federation and Football Supporters Europe, they appealed for information regarding the alleged incidents.
After receiving an "unprecedented response", Chelsea have chosen to take their case to UEFA.
"We issued a plea for information to those fans who may have been involved in these incidents," read a club statement on their official website.
"This resulted in an unprecedented response, with a large number of individuals coming forward to complain in relation to poor organisation, lack of crowd control, brutality on the part of stewards and police and exposure to generally unsafe conditions.