Up to 10,000 Manchester United fans are expected to travel to Rome without tickets for next week's Champions League final against Barcelona, the British Foreign and Commonwealth Office (FCO) said on Tuesday.
In a statement, the Foreign Office warned fans which metro stops and other areas of the city to avoid because of the fears of widespread trouble surrounding the match in the Italian capital.
There have been many stabbings, fights, muggings and thefts involving overseas fans in Rome for a number of years and the Foreign Office has warned United fans to take every precaution.
Typical of the advice handed out is: "Do not take the metro to the Piazzale Flaminio or use the Ponte Duca D'Aosta bridge as there has been trouble along this route to the stadium on many occasions."
UEFA threatened to take the final off Rome if AS Roma's Champions League quarter-final against Manchester United last season was marred by a repeat of the violence that hit United's previous two visits.
That did not happen but Arsenal fans were attacked before their team knocked out Roma in a last-16 second leg in March.
In a statement, the FCO says it worried about the number of fans making the trip which is estimates will be 30,000. Twenty thousand fans are expected to travel with tickets.
"Whilst last year's Champions League Final in Moscow saw exemplary behaviour from British fans, the Foreign Office is concerned that the sheer amount of fans travelling to Rome could lead to safety issues in the Italian capital," the FCO said in the statement. "It has therefore worked in close collaboration with the Italian authorities to put in place stringent safety plans, as well as offering crucial tips and advice to fans before they travel. These can be seen in full on a dedicated webpage on the FCO website."
The Foreign Office also says that the excitement generated by "the dream final" between two of Europe's most glamorous and successful clubs, will lead to more last-minute decisions to travel to Rome next week, thus increasing the likelihood that British fans will experience difficulties.
"One in five Brits neglect to take out any form of travel insurance and this number dramatically increases with last-minute planning and short stays.
"The FCO is particularly worried that the current economic climate means that more fans will be cutting corners and will decide against taking out travel insurance. This could have potentially disastrous consequences for football travellers, as a fall in Rome resulting in a broken leg could cost up to 2,500 pounds without insurance."
Gianni Alemanno, the mayor of Rome, added: "We are delighted to be hosting such a fantastic event and we have worked hard to ensure that all visitors have an enjoyable and trouble-free stay in our city. Rome welcomes the British fans with open arms, and we look forward to celebrating this great sporting festival together."
The FCO has also released safety tips - available at www.fco.gov.uk/football - which have been created in cooperation with the Italian authorities to help fans prepare for their trip to Rome:
You must carry original photo ID with you to enter the Stadio Olimpico. This can be a UK passport or a UK driving license. Take a photocopy of your passport and keep it separate to the original. Take out travel insurance. Without travel insurance you could be liable to pay thousands of pounds should you have an accident that involves hospital treatment or repatriation. Get a European Health Insurance Card (EHIC - formely known as E111). The EHIC entitles you to low cost or free healthcare in most European countries in an emergency, but you will still need travel insurance cover. Make-up containers and coins will not be allowed into the Stadio Olimpico so be sure to empty your pockets before heading to the match. Do not take the metro to the Piazzale Flaminio or use the Ponte Duca D'Aosta bridge as there has been trouble along this route to the stadium on many occasions. Use the free public transport provided by the authorities at Villa Borghese (entrance to V. Borghese is at the top of the famous Via Veneto) to get to the stadium and don't travel to the stadium on foot or by other means including taxis or other public transport. There will be no public screens in Rome so it is important to plan where you will watch the match if you are travelling without a ticket. Stay as far away as possible from Campo De Fiori - there has been trouble in this square in the past amongst football fans. Take care of your valuables in busy areas and on public transport - pick-pockets may be operating. Be especially wary around the main railway station, Termini, on the number 64 bus, and when unloading baggage from airport/city coaches. Be wary of groups of children who may try to distract your attention whilst trying to steal from you. Don't carry all your valuables - passports, credit cards and money - in the same bag or pocket. Don't carry valuables around with you unless you need to - consider putting them in a safety deposit box in your hotel. Cars at rest stops and service stations can be targets for robbers - if you find yourself with a flat tyre, especially on the Naples to Salerno motorway, treat any offers of help with caution. Store your valuables securely on sleeper trains - thieves have been known to operate on them.