Mirvish Productions is the latest casualty of the G20 as the theatre powerhouse announced Friday it would be cancelling all shows during the high-profile government summit.

The cancellation means that the hit play Mamma Mia will end its run a week early on June 20 rather than June 27. Performances of Rock of Ages will also be affected.

"It wasn't an easy decision to make," said producer David Mirvish. "The theatrical adage we have always lived by is ‘the show must go on.' But in this instance -- an unprecedented instance for us as we've always performed our shows -- we have concluded that our audiences are best served by the shows not going on."

Stringent security, road blocks and rowdy protesters are all expected to mark the city when the world's most powerful leaders in government and the financial sector come to Toronto on June 26 and 27,

The Royal Alexandra and Princess of Wales theatres are located at the edge of the G20 security zone on King Street West. Earlier this week, officials with Mirvish Village said they were confident the summit would not interfere with theatre goers.

But on Friday, the theatre company said information about traffic regulations on King Street that week "appears to be inconclusive or contradictory."

Mirvish called the situation "a shame."

Ticket holders who have had their shows cancelled will be contacted and offered an exchange to other Mirvish performances.