A US company with the word "Bing" in its name has sued Microsoft for branding its search engine with the same word, alleging trademark infringement and unfair competition by the software giant.

Bing Information Design filed the case in a St. Louis circuit court, seeking damages including corrective advertising paid for by Microsoft to eliminate confusion between the brands, the company's law firm said in a statement.

The design company, which offers computer-related illustrations and other services, has used the name Bing since 2000 and applied to register the trademark "Bing!" on 26 May, according to US Patent and Trademark Office records. The USPTO initially refused the application on 25 August

Microsoft filed its application for the trademark "Bing" (without the exclamation mark) on 2 March.

Microsoft's use of the name Bing and its aggressive advertising have "gutted" efforts by the small design company to distinguish itself, the statement said. Bing.biz, a website linked to in the statement, showed sample graphics from the company and gave the job titles of its two principals as "overlord-in-chief" and "the brains behind the operation."

Microsoft has not been served with a complaint but is aware of the lawsuit based on media reports, a Microsoft spokesman said.

"We believe this suit to be without merit and we do not believe there is any confusion in the marketplace with regard to the complainant's offerings and Microsoft's Bing product," the spokesman said.

Microsoft launched its Bing search engine earlier this year as a revamp of its Microsoft Live Search service.