Manchester United fans have been told they will be arrested if they don't have tickets for the match
But with safety measures being stepped up after the Dortmund bus explosions last night the mayor of Brussells has decided to take precautions into his own hands.
And he has said any United fans without a ticket for the match will be administratively arrested.
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Man United train ahead of Europa League clash with Anderlecht Wed, April 12, 2017
Manchester United have been training ahead of their Europa League clash with Anderlecht
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Manchester United have been training hard ahead of their clash with Anderlecht
Dortmund's game with Monaco was postponed by 24 hours after yesterday's bus explosions.
Marc Bartra injured his hand and was taken to hospital for surgery and the game had to be rescheduled for this evening.
Increased measures mean the city and all public events within it are subject to enforced security procedures, including army presence, extra security sweeps and controls.
United arrived in the Belgian capital this afternoon and, as always, had been in contact with the Consulate and local authorities.
The mood around Anderlecht's Constant Vanden Stock Stadium is calm on the eve of the quarter-final clash and United fans were advised of increased security measures before the attack in Dortmund.
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The message to travelling supporters on the club's official website read: "No bags at all will be permitted inside the stadium, including handbags.
"Unfortunately there are no storage facilities at the stadium, so we advise you not to travel with bags.
Paul Pogba gears up to face Anderlecht in training this week
"This strict policy has emanated from concerns over terrorist incidents and will be very strictly enforced."
United fans were told they will be "searched on arrival, at the turnstiles by police" and ticket checks will take place at various points.
The information also said: "Fans without tickets are being told not to travel as they will not get into the stadium.
"Belgian police advise that all supporters without tickets on the territories of Anderlecht will be administratively arrested, by decision of the Mayor."