United Parcel Service (UPS) is the latest to join a list of companies suing internet advertising company Gator, according to media reports. In its lawsuit, which was filed in a district court in Atlanta, the parcel carrier claims that Gator’s practice of putting ads on the UPS web site without permission causes “consumer confusion and complaints.”

Gator’s software manages passwords and fills out application forms for about 22 million internet users. The company also produces software that monitors web surfers’ behaviour and delivers pop-up ads, paid for by Gator’s clients, which can be set to appear when the surfer is on a rival’s site. The ads are only seen by those who download Gator’s software.

UPS, which does not run outside advertising on its web site, says that the Gator pop-ups not only advertised “dating services and on-line physics”, but also rival company FedEx. It is seeking unspecified damages and a court order to stop Gator’s practice in future.

In June, Gator was sued by a group of publishers and media companies, including The Washington Post, The New York Times, Dow Jones & Co and Knight Ridder Digital. They claimed that Gator infringed on their copyrights and trademarks and stole their revenues by putting unauthorised pop-ups on their web sites.

We are processing your request. \n Thank you for your patience. An error occurred. This could be due to inactivity on the page - please try again.