UEFA are set to begin a formal investigation into what the causes were for the chaos outside the Estadio do Dragao earlier this week as a large number of Inter fans were denied entry despite holding tickets for the Champions League match against Porto.

This according to today’s print edition of Turin-based newspaper Tuttosport, via FCInterNews, who report that blame for the incident could fall on Porto for the ticket-taking system at the stadium.

Whilst so far UEFA have only mentioned the fact that some Inter fans held tickets to the section of Porto’s stadium where Nerazzurri supporters were not allowed to be in in the organization’s press release, this will not be the key focus of the investigation.

According to Tuttosport, the real question will concern why Inter fans were denied entry en masse in “neutral” sections of the stadium.

Given that the two clubs had agreed upon a prohibition on Inter fans sitting in the section where Porto’s ultras sit, there is no issue with the fact that the Inter fans who had managed to buy tickets for that section were denied entry.

However, Tuttosport note, this makes up for only a small number of the Inter fans who were barred from entering the stadium.

Rather, the newspaper highlight, of the hundreds of fans left in the chaos outside the stadium, the vast majority held tickets for the “neutral” sections.

Accordingly, Tuttosport speculate, the issue could be that some aspect of the ticket-taking system at the gates of the do Dragao was systematically excluding ticket-holders with Italian surnames, thus causing a large number of fans to be left outside leading to the chaos.