The NEC Group last night launched an extraordinary attack on Karren Brady, accusing the Birmingham City FC managing director of behaving dishonourably over the super-casino issue.
A senior NEC official said Ms Brady had damaged the reputation of Birmingham and the West Midlands with her outspoken criticism of the NEC super-casino plan.
Debbie Thomas, head of press and PR for the NEC Group, claimed Ms Brady had broken an agreement that neither Birmingham City nor the NEC would "rubbish in public" each other's scheme.
Ms Thomas said a deal to keep the lid on unhelpful publicity was reached earlier in the year during a meeting between Ms Brady, NEC Group chief executive Andrew Morris, and Birmingham City Council interim chief executive Stephen Hughes.
The agreement, designed to show the Government that Birmingham was approaching the casino debate in a united and constructive way, was sealed by a handshake and witnessed by Mr Hughes.
The NEC has grown increasingly frustrated at Ms Brady's outspoken language and in particular her ability to generate media coverage.
Ms Brady's claim in a newspaper article that the NEC needed the financial fillip from a super-casino because it was a "failing business" appears to have been the final straw.
Ms Brady claimed the NEC super-casino bid had no chance o f gaining Government approval because it did not meet the criteria for triggering regeneration in deprived areas, whereas the Birmingham City casino plan met all those requirements.
Business groups who were prepared to "do the bidding of their commercial partner the NEC" would throw away a once-in-a-lifetime opportunity to revitalise a huge area of inner-city Birmingham if the Blues' casino and stadium scheme was rejected, Ms Brady added.
NEC management fear the debate may explode in an even more damaging way in the run-up to Monday's cabinet meeting, when council leaders are expected to formally back the NEC casino proposal and reject the Birmingham City scheme.
Miss Thomas said: "We believe we have adhered to the spirit of that handshake. Ultimately, this is about winning a casino for the region, it is about getting jobs and regeneration, and it should not be something that is ripping the city Karren Brady claims she loves so much in two."
Claims that the NEC was struggling financially were totally without foundation, Ms Thomas added.
"The NEC Group generates £1.3 billion for the regional economy every year. It is a huge success story," she said.
Suggestions that the number of jobs to be created and the financial benefits of an NEC super-casino had been exaggerated were also denied.
MGM, the NEC's casino partner, had based the projection that a super-casino would generate £350 million profit over ten years on its vast experience of the gaming market.
"MGM have developed casinos across the world. They know what they are talking about," Miss Thomas added.