Celtic supporters were attacked in Rome after their shuttle bus broke down and was ambushed on the way back from the Stadio Olimpico.
It is not yet known if any fans sustained serious injury following their side's 2-1 Europa League victory over Lazio.
READ MORE: 'Celtic fans' stabbed by masked men outside bar in Rome
Earlier in the week, two Celtic fans were stabbed in the leg by masked men outside the Flann O'Brien pub in the city.
Their injuries are not life-threatening.
Tensions between the two sets of fans were high after Mussolini's granddaughter demanded Hoops fans who displayed a banner depicting her fascist grandfather's hanging body be prosecuted.