London - Scottish police have arrested 12 men after illicit banners were displayed at the politically-charged Champions League clash between Celtic and Linfield last month.
UEFA, European football's governing body, charged the Scottish champions over the illicit banners and blocked stairways during the qualifying round clash with Linfield at Parkhead on July 19.
Linfield fans are drawn from Northern Ireland's Protestant community, putting them at odds with Celtic, who are historically seen as a Catholic side, and there were pitch invasions and missiles thrown during the first leg in Belfast.
Celtic responded to the UEFA charge by imposing a two-game closure on the section of their stadium used by the ultras-style 'Green Brigade' fans who displayed the banner.
Police Scotland on Tuesday said 12 men, aged between 18 and 49, have now been arrested after a "proactive police investigation into banners and material displayed".
They have all been released on an undertaking to appear at Glasgow Sheriff Court later this month.
Celtic's partial stadium closure, thought to have affected 900 season-ticket holders in the safe-standing section of the ground, will be lifted after the Scottish Premiership match against Hearts on Saturday.
However, the Glasgow club said "a number of fans within this area remain suspended" while investigations continue.