Rapid Response is seeking an injunction to stop National Breakdown from using the term "rapid response" and a stylised letter "R" in a multi-million pound advertising campaign for a roadside help service.
While Rapid Response uses a lower case "r" in a rectangular setting, National Breakdown sports a capital "R" in a circle.
Brian Wright, the founder of Rapid Response, said in an affidavit obtained by the Independent on Sunday that it would be "catastrophic" for his business if Green Flag subsidiary were allowed to use the slogan and a similar logo. "We may not survive as a business," he claimed.
Mr Wright already believes a deal with Securicor, a large security firm, has fallen through because of the National Breakdown campaign. And that deal was key to securing several others, he said.
Mr Wright acknowledges in his affidavit that his Rapid Response name and logo were not secret. He also states that he approached Green Flag about forming an alliance.
Rapid Response filed for trademark protection in 1993, but it is not due to be granted until next month.
Ernest Smith, the chairman of Green Flag, said he planned to fight the injunction vigorously.
"This is nothing more than a spurious claim by an opportunist, which is attempting to benefit from our success," he said. A hearing will be held in the Manchester High Court on 14 July.