Security curbs affecting flights have forced a New York orchestra to cancel an Edinburgh Festival concert and a BBC Proms appearance, it has emerged.
Recent security measures hit the orchestra's travel plans
An Edinburgh International Festival spokesman said the Orchestra of St Luke's was deeply disappointed it could not overcome travel restrictions.
Meanwhile, festival ticket sales have topped more than £2m even before the official opening concert on Sunday.
Strauss' Elektra kicks off the festival in the capital's Usher Hall.
New security measures established following last week's air terror alert have seen a ban on taking all but the most essential items into aircraft cabins, long delays and flight cancellations.
The festival spokesman said the Orchestra of St Luke's could not make dates at the festival on Wednesday or the Proms on Thursday due to limitations on international travel.
He added: "Despite the best efforts of all involved, it has proved impossible to surmount the obstacles in the very short time available.
"The orchestra and its conductor, Donald Runnicles, are deeply disappointed that these concerts cannot take place and hope to return to Europe in the near future."
Ticket holders are being offered seats at an alternative performance or a refund. The BBC Proms hope to make an announcement about a replacement concert soon.
All other festival events are currently said to be going ahead as planned.
Meanwhile, EIF ticket sales have hit the £2m mark nearly two weeks earlier than last year.
Classical music sales have been particularly strong, with more seats sold already than during the whole of the 2005 festival.
Performances of theatre, opera and dance will also get under way across the city following Sunday's opening concert.
Festival director Brian McMaster said: "I am really pleased that people have booked in such numbers for a wide range of events, including a less familiar play by Shakespeare, Indian Dance, and new writing.
"But the real excitement is that we've sold more seats this year to classical music.
"The festival is a time to try new experiences and I hope people will continue to take risks with us for the next four weeks."