MP3-player maker Creative Technology followed through Monday on its threat to defend one of its patents, suing Apple in federal court for infringement and filing a complaint with the US International Trade Commission.

The Singapore-based company alleged in both complaints that Apple was violating its "Zen" patent--named for its Zen line of MP3 players--that covers its navigation system and method for organizing and accessing music on portable players.

"The iPods and iPod Nanos sold by Apple are specifically configured to access and display music loaded by the user in ways that infringe the asserted patent," Creative Technology said in the complaint.

Creative asked the trade commission to investigate the alleged patent violation.

It is seeking unspecified damages in the lawsuit, filed Monday in US District Court in San Francisco, and is also asking the court to prohibit Apple from selling and importing iPod and iPod Nano products into the US from China, where they are made.

In the trade complaint, Creative said it landed the Zen patent in August 2005 and first used the navigation system in its Nomad Jukebox player in January 2000 and has been using it in all of its Nomad and Zen players ever since.

According to the complaint, Creative execs met with Apple chief Steve Jobs in early 2001 to resolve the matter, and that Apple requested to license Creative's technology.

Creative said it rejected that proposal, as well as a second offer from Apple to invest in a potential spin-off of Creative's music-player business.

The meeting and the proposals preceded Apple's October 2001 launch of the iPod, the most dominant portable music player on the market. The iPod claimed 72 percent of the portable music-player market in 2005, according to NPD Group, and has approached 80 percent in the first quarter of 2006. Apple has sold 51 million iPods since their introduction.

Meanwhile, Creative has largely struggled, despite releasing products that have been widely praised.

Creative's move comes just two weeks after the company reported its worst-ever quarterly loss, citing a drop in memory prices and costs to reorganize a unit. Creative saw sales of its MP3 players fall 51 percent in the third quarter from the second quarter.

Apple, which declined to comment on the case, filed its own patent application for the interface and navigation system, but saw that application denied because of Creative's patent.

When Creative won the patent last August, CEO Sim Wong Hoo said his company would aggressively defend it and touted his company's focus on technology as the "key difference between a technology company and a branding company."

Shares in Apple dropped $2.08, or 3 percent, to $65.71 in late-afternoon trading, while shares of Creative rose 29 cents, or 5.3 percent, to $5.75.