(ECNS) -- Customs officials in the eastern Chinese city of Qingdao have busted a ring suspected of smuggling more than 5,000 tons of high-end seafood in two years, including products from Japan possibly contaminated by radioactive water, China Central Television reported.

The investigation started after officials found retail prices for some premium seafood products in Qingdao of Shandong province were clearly below the market price for imports early this year. Some fish were also transported by vehicles licensed in South China's Guangxi Zhuang Autonomous Region, further raising doubts over legitimacy of the products from Japan, Russia and the United States.

An importer in Shandong province was later found to have branches in several provinces and its boss Wang also had a subsidiary in the United States that was responsible for all international contacts.

Wang, who spent most of his time in the US, was caught at an airport on June 24 when he returned. Subsequent investigations in several regions found his companies smuggled seafood with a market value of 230 million yuan ($35 million).

Some seafood products were also found to have originated from waters near Japan's Fukushima Daiichi nuclear plant. China banned Japanese food imports from 12 areas following the Fukushima nuclear incident in 2011.

Smugglers changed the packaging or production dates for seafood from questionable areas and then took much longer journeys to cover their tracks, including a stop at Fangchenggang city in Guangxi, officials said.