SAN FRANCISCO ? Rosetta Stone, a language-learning software producer, on Friday filed a federal lawsuit against Google for infringing its trademark through Google's AdWords online advertising program.

Rosetta Stone charges that Google is wrongly allowing its name and other trademarks to serve as keywords that other businesses can use to target paid advertisements to people on the Internet.

Google told AFP on Friday that it had yet to be served with a copy of the lawsuit and so could not comment on specifics, but confirmed its policy is to allow trademarks to be used to target AdWords advertising.

"We allow trademarks to be used as keyword triggers in AdWords because users searching on Google benefit from being able to choose from a variety of competing advertisers," said Google spokesman Andrew Pederson.

"Just as it's reasonable to expect a range of brands on any shelf in a grocery store, providing users on Google with more than one option when they search for a brand name or other trademark helps them to find the best product at the lowest price."

Google has held its ground in similar lawsuits, which have yet to be resolved in court.

In May, Google adjusted its trademark policy in AdWords in the United States to allow some ads to use trademarks without permission, saying the change brought the California company more in line the industry standard.

"This change will offer you the opportunity to provide users with more relevant information, choice and options while respecting the interests of trademark owners," Inside AdWords crew member Dan Friedman told Google advertisers in a May message at the firm's official blog.

Rosetta argues that Google's policy results in consumers being deceived or confused.

"Google's search engine is helping third parties mislead consumers and misappropriate Rosetta Stone trademarks," said Rosetta Stone general counsel Michael Wu.

"Google and its advertisers benefit financially from and trade off the goodwill and reputation of Rosetta Stone without incurring the substantial expense that Rosetta Stone has incurred in building up its popularity, name recognition, and brand loyalty."

Rosetta Stone is asking the court to bar Google from using the firm's trademark in AdWords.