Celtic to investigate after fans & Swedish police clash in Stockholm
Celtic say Swedish supporters entered the away end as fans and local police clashed in Stockholm during their 4-1 Europa League play-off win over AIK.
Pictures from the Friends Arena showed officers using batons on the travelling fans, and flares were also lit in that section of the ground before kick-off.
Celtic say they are now conducting their own investigation.
"We are aware that a number of Swedish supporters entered the area for visiting fans and we are currently investigating events," a club spokesperson said.
After the match, manager Neil Lennon said he was unable to comment, adding, "I don't know what the issue was," he said following his side's 6-1 aggregate victory. "How could I see that, I'm on the touchline? Our fans are impeccable away, so I hope no one was hurt."
Following their triumph, Celtic will be in Friday's group stage draw - alongside Rangers - at 12:00 BST.