German police have spoken of concerns about an intelligence gap in the level of aggression of the latest generation of England football fan, as supporters gather in Germany for the first post-Covid Euros.

England’s Sunday evening tie against Serbia in their first game of Euro 2024 has been designated as “high risk” due to a heightened threat of violence between two groups of supporters with a history of thuggery.

Peter Both, the police chief in the host city of Gelsenkirchen, said the abnormality of the 2020 Euros made it difficult to judge how the current generation of young men in their 20s would behave.

He said: “There is one area where we perhaps all have a bit of a blind spot. If you look at the fact the last major tournament which you could really travel to from almost anywhere, I mean the last public tournament, was the 2016 European Championship, and this was eight years ago.

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“Since then, the fan scenes have, of course, developed. And today these fans are in their mid-20s, so they are at a stage where they might also switch to becoming part of an aggressive camp of fans, but, of course, it makes it difficult for us to predict exactly what will happen.”

Both said this had led the German police to “take a few more safety precautions than at other games”, including the decision to serve only low-alcohol beer in the Veltins-Arena, which is home to the Bundesliga club Schalke.

The Euro 2020 tournament was due to be played between 12 June and 12 July 2020 but was delayed to 2021 due to the pandemic and a range of restrictions remained in place.

Serbian football has long been tarnished by hooliganism and there has been a rise in disorder in the English domestic leagues in recent years after a period of improved behaviour on the terraces.

As of last summer, there were 1,624 football banning orders in force, an increase of 24% compared with the previous year. Within the 2022 to 2023 football season, 682 new banning orders were issued, an increase of 32% compared with the 2021 to 2022 football season.

Those under such orders have been forced to surrender their passports to the police from 4 June until the final on 14 July, to ensure they do not attempt to attend matches in Germany.

Both said while the FA had been given an allocation of 10,000 tickets, he believed that 20,000 had been sold to England fans for Sunday’s game and that more than 30,000 were now expected in the city.

An estimated 10,000 Serbian fans are expected, although Both said it was difficult to monitor as “in Serbia, they can just get in the car and drive [to Germany]”.

Earlier this week, Both had told the Guardian he feared that up to 500 “violence-seeking” Serbian hooligans could travel to Gelsenkirchen for the game, but he reiterated on Friday that the authorities still lacked “concrete information”.

He said: “The only thing we have said time and again, and which I would like to emphasise again now, is that we cannot rule it out. There is no international tournament that I can remember that has remained peaceful for more than four weeks every day.”

He also cautioned about “fake news” shared on social media about outbreaks of violence before the tournament and claims that Albanian fans had attacked the Serbian national team.

He said: “I sincerely ask that we actually keep calm a little, especially before such a high-risk match.”

England fans without tickets are being encouraged to go to a fan zone at a racecourse, where organisers said there would be 80,000 litres of beer, 40,000 bottles of soft drinks, 7.5 tonnes of chips and 32,000 sausages.