CELTIC have launched their own probe into trouble involving their fans in Stockholm during a vital Europa League match.

Celtic fans were believed to be involved clashes with Swedish police during their victory over AIK which took the side into the group stages of the Europa League.

Officers wielded batons as punches were thrown during the stadium confrontation. Four people were arrested after Swedish fans clashed with police at Celtic Park in the first leg.

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Flares were seen to be ignited during the Europa League clash by fans in the Celtic end of the ground.

Celtic have defended their support and launched an investigation after claims rival Swedish fans stormed the away section at the Friends Arena. It is believed the fans may have been supporters of AIK's fierce rivals Hammarby.

Several fans are said to have suffered minor injuries and the scenes look certain to be reported back to Uefa.

A spokesman for the Scottish champions said: "We are aware that a number of Swedish supporters entered the area for visiting fans and we are currently investigating events.

The Herald:

“It was clear many Hammarby fans were in the Celtic sections and this was raised by Celtic officials before the match.

“A lot of Swedish fans managed to infiltrate the away section which we believe was a major factor in the issues which arose, there was a lack of control at the access points to the Celtic section.”

READ MORE: Four arrested at Celtic's Europa League game with AIK

Swedish journalist Robert Laul, who witnessed the brawl, said: "Quite crazy scenes as Celtic fans fight with guards."

Celtic manager Neil Lennon who had seen his side qualify for the group stages of the Europa League with a victory said: "I don't know what the issue is but our fans have been impeccable and I hope nobody is hurt."