According to the Wall Street Journal report, Six Continents Hotels is also accusing Gator of computer trespass and unfair competition, albeit the ads only appear where internet users have installed Gator's software.
The hotel chain says that its business relations are affected and its customers are confused, because Gator is placing pop-up ads for discount agents selling competitors' rooms on the Six Continents Hotels web sites.
Earlier this month, Gator filed a lawsuit asking a federal court in San Francisco to declare that placing pop-up ads on other companies' web sites does not violate the rights of the sites' operators.
Gator is currently facing other lawsuits over its pop-up ads filed by major companies, including the Washington Post and United Parcel Service.