Chelsea have appealed for witness accounts from supporters who travelled to Wednesday's Champions League match against Barcelona after claiming "a number of fans were hurt" in alleged incidents outside Camp Nou.
It meant a 4-1 exit on aggregate at the last-16 stage but, after Antonio Conte's post-match briefing, Chelsea requested information from anyone caught up in reported altercations before kick-off.
Several fans took to social media to complain of rough treatment from Spanish police and stewards.
A Chelsea spokesman said: "We are aware of reports of incidents outside the ground before the game where a number of Chelsea fans were hurt.
"We ask that our supporters contact us with accounts of their experiences of this evening's arrival at the stadium so that we can take this up properly with the authorities."