Supporters encouraged to dress "conservatively" on trip to Rotterdam.

Manchester United have advised fans travelling to Thursday’s Europa League tie against Feyenoord not to wear club colours.

The club wrote to supporters letterin the wake of safety concerns in Rotterdam following crowd trouble involving the Dutch side.

Earlier this month, United fans hit out at the reduced ticket allocation they are receiving for the fixture, which saw oubreaks of trouble when the clubs met in 1997. They believe United are being ‘punished’ for the misbehaviour of other team’s fans.

The Times reported that United supporters have been issued 1,400 tickets for the game at the De Kuip stadium, which is set to host just half of the usual 52,000 capacity.

The Dutch club are to cut their capacity in a bid to avoid triggering suspended punishments they were handed by UEFA for crowd trouble.

The letter, reported in the Manchester Evening News, reads: “For your own safety it is advisable to maintain a low profile and avoid areas of potential conflict and by dressing conservatively.

“Once the game has ended, and Manchester United supporters are all out of the stadium, a special 1,200 seat train service will be provided from the stadium rail station. The service will stop at both Rotterdam and Amsterdam train stations.

“Please ensure that you carry your passport at all times, as required by law in the Netherlands. There is currently a general high threat level from terrorism in Europe and you should ensure that you are mindful of your own personal safety and security whilst travelling.

“Finally, we hope that you enjoy your visit to the Netherlands and thank you for your support.”