Apple's iPads have been banned from sale in part of China after a local firm claimed it had rights to the tablet computer's brand name.
The row with Shenzhen Proview Technology threatens to complicate Apple's sales efforts in the country, its fastest-growing market.
Investigators started seizing iPads on Thursday in the northern city of Shijiazhuang following complaints from Shenzhen Proview, said a spokesman for the economic investigation department.
"All the Apple iPads in the big shopping malls and supermarkets have been taken off shelves in Xinhua district," said the spokesman.
Apple has five stores in mainland China - two in Beijing and three in Shanghai - and authorised outlets in other cities.
Shenzhen Proview registered the iPad name in China in 2001. Apple bought rights to the name from a Taiwan affiliate, Proview Taipei, that registered it in various countries as early as 2000. The mainland company says it still owns the name in China.
A Chinese court rejected Apple's complaint in December that Shenzhen Proview was violating its rights to the iPad name. The court ruled Proview is not bound by a 2009 agreement under which Proview Taipei transferred the trademarks to Apple.
Shenzhen Proview says it filed a trademark violation complaint in January with the commercial bureau of Beijing.
The company has asked more than 20 cities to investigate and to destroy promotional materials that violate its trademark.