Champions League: Chelsea fans 'hurt' at Nou Camp before Barcelona game
Chelsea have been "made aware of incidents" outside Barcelona's Nou Camp before Wednesday's game in which "a number of fans were hurt".
Videos on social media show clashes between fans and security before the Champions League last-16 second leg.
Mossos d'Esquadra - the Catalan police force - told BBC Sport they have not received reports of any incidents.
Chelsea have asked fans to contact them about their "experiences" of arriving at the stadium.
"We are aware of reports of incidents outside the ground before the game where a number of Chelsea fans were hurt," said the club.
"We ask that our supporters contact us with accounts of their experiences of arrival at the stadium so that we can take this up properly with the authorities."
The Chelsea Supporters' Trust (CST) said it was gathering evidence to send to European football's governing body, Uefa.
CST chairman David Chidgey said: "If we can put together a decent case and the club take that to Uefa, backed by the supporter organisations, something might actually register with Uefa.
"The club take it seriously and we work as closely with them as we can to get the evidence to them and support them."