China is cracking down on smugglers bringing Apple iPhone 6 smartphones into the country ahead of their official release, with officials on Sunday reporting the seizure of 453 of the devices in Shanghai.

Hundreds more were seized during three separate raids on Thursday through Saturday in Hong Kong, Xinhua News Agency said.

The latest haul was found in the luggage of two passengers arriving at the Shanghai airport from Tokyo, one of them Chinese and one of them Japanese, the Shanghai customs agency said.

Hundreds more have been confiscated from passengers who did not declare them at customs, the agency said.

Apple delayed its original plans to introduce the iPhone 6 in China this month but did not comment on reports that it still hadn't received Chinese regulatory approval.

The already thriving black market for the phones in China, where Apple competes with less-expensive alternatives from local manufactures Xiaomi and Lenovo, plus Samsung, has drawn a rebuke in Chinese State media.

Apple came in for criticism from the media last year when it was reported for fixing internal components of faulty iPhones in China under warranty but elsewhere was replacing faulty phones. Apple later clarified that it would be replacing handsets in China and apologized about the concerns, and the furor subsided.