Manchester United fans without tickets have been warned not to travel to Thursday's Europa League quarter-final against Anderlecht amid high security around the game in Belgium.
Around 1,300 English supporters are gathering in the Belgium capital Brussels for the game with the city on high alert following Tuesday night's bomb attack on the Borussia Dortmund team bus ahead of their Champions League quarter-final against Monaco.
There are also fears about the chances of clashes between supporters following several incidents involving fans of another English team, Leicester City, in Madrid before Wednesday's game against Atletico.
Spanish police used baton charges to clear part of Madrid's Plaza Mayor of Leicester fans, some chanting "Gibraltar is ours", a reference to the recent diplomatic spat between Britain and Spain over the British Overseas Territory.
BBC presenter Gary Lineker, a Leicester City fan and former player, tweeted: "Just saw the footage of some Leicester fans behaving despicably in Madrid. The few idiots ruin it for the decent majority. Sickening."
There has been a history of trouble between English sides and Anderlecht stretching back to 1984 when a Tottenham Hotspur fan was shot before the Uefa Cup final between the clubs in Brussels.
In 2015, Tottenham fans were attacked by Anderlecht supporters while drinking in a bar ahead of the Europa League tie.
(For more sports news and updates, follow Ahram Online Sports on Twitter at @AO_Sports and on Facebook at AhramOnlineSports.)