Police and customs officials investigating suspected patent violations seized dozens of boxes of mobile phones, navigation devices and other gadgets from exhibitors in a technology fair, authorities said Thursday.

Police in Hanover said more than 180 officials were involved in the searches Wednesday at the annual CeBIT trade and technology fair in that central German city.

They did not identify the people or companies concerned, but they said "the background is the number that has been rising for years of criminal complaints by the holders of patent rights in the run-up to CeBIT."

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Police said they filled 68 boxes with gadgets, documents and advertising material. The gadgets included cell phones, navigation devices, electronic picture frames and flat-screen devices, a police statement said.

All the exhibitors who were searched cooperated, except one who was briefly taken to a police station, police said.

Of 51 exhibitors affected, 24 were from mainland China, three from Hong Kong and 12 from Taiwan. Another nine were German, and one each were from Poland, the Netherlands and Korea.

The alleged patent violations largely concerned devices with MP3, MP4 or digital video broadcast functions, as well as DVD players and blank CDs and DVDs, police said.