The Olympics will cause "a bloodbath of a summer" for London theatres in 2012, Andrew Lloyd Webber has predicted.
"Nobody's going to go to the theatre at all," the composer told Radio 4's Today programme, predicting that "most of the theatres in London will shut".
"It's going to be very tough," he said, revealing advance bookings were "about 10%" of their normal level.
Three major musicals, he added, "are not going to play over the Olympics" - but he would not name them.
Lord Lloyd-Webber's Really Useful Group owns seven London theatres which are currently hosting shows including War Horse, Matilda and The Wizard of Oz.
The impresario said "big, big, big hits" like his own The Phantom of the Opera would continue during the Olympics period.
But he said some of his other theatres "will have to" close because of a drop-off in the "ordinary West End tourist audience".
On a brighter note, the 63-year-old said a host of new musicals would arrive in the West End after the conclusion of the 2012 games.
Shows heading into London include a Spice Girls musical, a Bridget Jones stage show and the Tony award-winning The Book of Mormon.
"They've never been so commercially popular," he told BBC arts correspondent Rebecca Jones. "The appetite for musicals is insatiable in a way.
"I don't think I've ever had so many musicals being offered to our theatres in London as there are for the end of next year."
The capital's promotional organisation London and Partners added that 29 shows would be running next summer, with an "unprecedented" number booking through to the autumn.
A spokeswoman said that a whole series of experiences would be on offer next year, including London's "world-beating theatre".