MGM Resorts International and Cadillac Fairview Corp. have both received letters complaining about their use of images of the Princes' Gates and the letters CNE.
Brian Ashton, president of the Canadian National Exhibition Association, says using the images and letters in development publications infringes on his company's intellectual property.
Ashton's letter says the association does not support casino development projects and did not give permission for its images to be used.
The letter came six days after MGM and Cadillac Fairview unveiled proposal for a casino resort, complete with a 1,200 room hotel and a permanent home for Cirque du Soleil.
The presentation featured the CNE in a plastic miniature display of the city and in drawings. They have also used the CNE's images in various newspaper advertisements.
"It concerns the CNEA that the unauthorized use of its images and official marks by MGM/Cadillac Fairview will mislead the public into the mistaken belief that the CNEA is actually part of your proposal or that, at a minimum, the CNEA supports the proposal," wrote Ashton. "We continue to assert that a development of such size and scale would mean the disintegration of the annual CNE."
MGM and Cadillac Fairview issued a statement saying they would review the complaint and respond if necessary, but also defending their actions.
"We have consistently stated that our vision for an integrated resort on Exhibition Place is subject to the city's approval," the companies said.
Toronto city councillors were expected to vote on the casino proposal in April, but the motion has since been delayed. The vote has not yet been rescheduled.