Creative Technology, the number two in the music player market, has asked the US International Trade Commission (ITC) to investigate claims that Apple's iPod infringes one of its patents.

The dispute is over Creative's Zen patent, awarded in August 2005, which covers navigation by menus and organisation of music on a portable music player.

Creative applied for the patent in 2001 and, since having it confirmed, has been threatening to sue Apple over its iPod.

"Creative is seeking an exclusion order and a cease-and-desist order against Apple Computer Inc," said the filing to the ITC.

"The orders would prohibit Apple Computer Inc from engaging in sales, marketing, importation or sale after importation into the US, or other infringing activities in the US with regard to the infringing iPod and iPod Nano products."

Creative has also filed in a separate case in the District Court for the Northern District of California that seeks an injunction and increased damages against Apple for "wilful" patent infringement.

Research from In-Stat earlier this month found that Apple had 49 per cent of the portable music player market, with Creative a distant second.

"Apple continues to dominate the market for MP3 players, particularly in the US," said In-Stat analyst Stephanie Guza.

"Apple competitors continue to face significant challenges, such as a constrained Flash memory supply, device and software integration, and the 'cool factor' associated with Apple's iPod line of products."

Creative made a loss of $114.3m last quarter, which it blamed on price cuts in the digital player market and unsold inventory.