The Foreign Office has warned Celtic supporters not to travel to Seville unless they have tickets for next Wednesday's Uefa Cup Final.
Final tickets are at a premium
It has posted a special warning on its travel advice service telling fans to stay away from the Spanish city unless they already have a match ticket and accommodation reserved.
As many as 50,000 Celtic fans are expected to arrive in the city in the next week, at least half of whom will not have tickets for the game against Portuguese side Porto.
The Foreign Office's travel website said that all tickets for the match on 21 May had already been sold and hotel accommodation was "impossible" to obtain.
Laws and customs
"Consequently, supporters who are without tickets and arranged accommodation are strongly advised not to travel to Seville but to make arrangements to watch the match on television at home," it says.
The statement adds that those lucky enough to hold match tickets will get a warm welcome in Seville, but visitors are warned to "respect Spanish laws and customs and follow, immediately, any instructions from the authorities".
It adds: "Seville will be crowded on the night of the match. The Spanish authorities will be doing their best to ensure that the thousands of Scottish and Portuguese fans who are expected enjoy a trouble-free visit.
"However, please remember that moving and processing such large numbers of people takes time and delays may occur at any time."
The final will be held at the Estadio Olimpico in Seville
The Foreign Office warns fans to allow plenty of time to reach the stadium and be prepared to queue for tickets to be processed at the ground.
It also warns that potential delays may occur en route to the match and at the airport on departure.
The British Embassy in Madrid is sending a team of consular officials to Seville to cover the period of the match and to assist Scottish fans and supporters in any way they can.
The FO statement asks that fans help the Madrid embassy team by "acting, at all times, in a sensible manner".