HANGZHOU - More than a tonne of fake jellyfish has been seized and the producers detained in eastern China, reports said.

Six suspects were detained in Zhejiang and Jiangsu provinces, said a press release issued by Huzhou police on social media platform WeChat last week.

Three were nabbed in April for selling artificial jellyfish in a rural market in Wuxing district. More than 150kg of the product confiscated.

One of the suspects, surnamed Yuan, said they had been producing the "seafood" for almost a year.

Their operation had made more than 70,000 yuan (S$14,000) in profits since June 2015.

Yuan confessed that he had learnt the trade from a "master" surnamed Jia in Jiangsu's Changzhou City.

This led the police to three other suspects, where more than a tonne of fake jellyfish was seized.

Jia's operation is estimated to have produced more than 10 tonnes of the fake food, and his profit was estimated to be about 100,000 yuan.

Three chemicals - sodium alginate, calcium chloride and aluminum sulfate - were used to mimic the gelatinous texture of the delicacy.

There are high levels of aluminium in the mixture, 600 to 800mg/kg, which is eight times of China's own legal limit, the BBC reported.

The food and drug safety branch of Huzhou police said too much aluminium could result in bone and nerve damage, and potentially harm memory.

The effects could be more pronounced for pregnant women, children and the elderly.

The cost of producing fake jellyfish was less than half that processing real jellyfish, and less time was required, People's Daily Online reported.

Huzhou police also issued advice on differentiating real jellyfish from fake.

Fake jellyfish tends to be white and transparent, and it is tasteless and tough. Real jellyfish has a yellow tinge and has a fishy smell, the release said.