Lazio Football Club historian Alfonso Dessi has described Paolo Di Canio as a "true fascist" who had a "huge impact" on hooligan supporters because of his political ideas.
Dessi told ITV News that Di Canio's political views do not affect his football, but revealed his "bad temper" often got him into confrontation with Lazio's board.
Di Canio was confirmed as Sunderland manager yesterday amid a row over his political beliefs.
As a player, he had two spells with Lazio and is widely revered as a hero for the Rome-based team.
The Dean of Durham has said Paolo Di Canio's appointment as Sunderland manager "raises very difficult questions" because of the Italian's alleged links with fascism.
Reverend Michael Sadgrove admitted he was left "genuinely perplexed" at the football star's "unambiguous response" to media questioning of his political beliefs at his unveiling at the North East club yesterday.
In an open letter, posted on his personal blog, Rev Sadgrove said: "You say that you are not a racist, but it needs great sophistication to understand how fascism and racism are ultimately different.
"I can promise you that this distinction will be lost on the people of the North East where the British National Party is finding fertile ground in which to sow the seeds of its pernicious and poisonous doctrine.
"You did not necessarily know this before you came. But I believe that unless you clearly renounce fascism in all its manifestations, you will be associated with these toxic far-right tendencies we have seen too much of in this region."
The Sun has published a photo of new Sunderland manager Paolo Di Canio allegedly at the funeral of an Italian fascist.
The Italian football star reportedly attended the service for extremest Paolo Signorelli in Rome three years ago.
Signorelli had spent eight years in prison after being linked to a terrorist bomb attack which killed 85 people in 1980.
Paolo Di Canio refused to answer questions on whether he is a fascist but said the controversy surrounding his appointment was "ridiculous."Read the full story ›
Anti-discrimination in football group Kick It Out has urged Sunderland manager Paolo Di Canio to make a "full and frank commitment" against discrimination.
It is not part of Kick It Out’s remit to sanction the selection of staff of football clubs. However, football clubs have a responsibility to ensure that their employees demonstrate a commitment to anti-discrimination and equality of opportunity.
It may be in the interest of both the club and Mr Di Canio to acknowledge a full and frank commitment to these policies. It is all too easy for positive progress and engagement to be compromised by inappropriate statements, and both Sunderland supporters and members of its local community will be looking for reassurance on these points.
Sunderland's shirt sponsor Invest in Africa has confirmed that they are "reviewing" their relationship with the club, but denied that the review was down to Paolo Di Canio's controversial appointment as manager.
Former foreign secretary David Miliband quit as the club's vice-chairman over the Italian's past statements professing to be a "fascist but not a racist".
It had been reported that Invest in Africa were considering their position due to the controversial appointment of the former Swindon manager, but a spokesman for the sponsor denied that claim.
A spokesman told ITV News: "We have a one year sponsorship deal with Sunderland AFC with options to renew for the future.
"As a matter of course during this time in the sponsorship term and unrelated to events over the weekend Invest in Africa is currently reviewing its partnership with the club."
The Nelson Mandela Centre of Memory, which has a partnership with Sunderland AFC, has released a statement reaffirming its relationship with the club in light of Paolo Di Canio's appointment. The statement reads:
The Nelson Mandela Centre of Memory and the management of Sunderland Football Club met in England on Monday to discuss the public debates around Sunderland’s new coach. Mr Di Canio participated in the meeting ...
At the heart of the partnership is a commitment to our Founder’s values with a special focus on human rights and anti racism.
At the meeting on Monday Sunderland reaffirmed its commitment to these values and the ethos of the partnership.
It must be stressed that the Centre’s relationship is with the club, not with any individual in the club.
The organisation, which promotes the legacy of Nelson Mandela, formed a partnership with Sunderland last month.
The club has organised several fundraising events for its benefit, and plans to "utilise" its knowledge to "support football’s quest to eradicate racism".
Paolo Di Canio refused to talk about his political views during his first press conference since being appointed the head coach of Sunderland.
In the video below, he says he is "not in the House of Parliament" and then dodges ITV News' Martin Geissler's question about whether he still considers himself a fascist:
Paolo Di Canio will work alongside four other coaches who served with him at his former club Swindon, according to a statement on Sunderland AFC's website:
Following the arrival of new head coach Paolo Di Canio, there’s a few other new faces at the Academy of Light.
First team coach Fabrizio Piccareta, goalkeeping coach Domenico Doardo, fitness coach Claudio Donatelli and physiotherapist/masseur Giulio Viscardi have all joined the club’s backroom staff.
The four all served alongside Di Canio at Swindon Town from May 2011 to February 2013.