Fans among a section of supporters called The Green Brigade, unfurled a banner during half-time which read: "Your deeds would shame all the devils in Hell. Ireland, Iraq, Afghanistan. No bloodstained poppy on our Hoops."

Celtic responded to the controversy by issuing a statement on the club's website which said: "The actions of this small minority have no place at Celtic Park.

"We are currently investigating the matter and, clearly, we apologise for any offence caused."

Some fans of the club, which has a strong Irish Catholic heritage, refuse to support the Poppy Appeal because of the legacy of the Troubles in Northern Ireland while the Green Brigade are known for demonstrating support for Irish republicanism at games.