Crabs are on sale at a store in Causeway Bay in Hong Kong on Tuesday.Parker Zheng / China Daily

But some importers refused to suspend sales, claiming that they source their crabs from other farms and the two concerned farms only handle import paperwork for them.

Two samples of hairy crabs, imported from Wujiang Wanqing Taihu Crab Breeding Co and Jiangsu Taihu Aquatic Product Co, were found to contain 11.7 picograms and 40.3 picograms per gram of dioxins and dioxin-like polychlorinated biphenyls respectively. The toxic chemical compounds can lead to reproductive and developmental problems, damage the immune system, interfere with hormones and cause cancer.

According to the Center for Food Safety in Hong Kong, the acceptable level of the two chemicals contained in food is 6.5 picograms.

The center on Tuesday released a list of 15 local importers that sell the tainted hairy crabs, urging them to suspend sales and imports from the two Jiangsu suppliers.

Wah Kee Wing Cheong Ho is among the 15 importers. Stephen Chu, director of the 50-year-old company, told China Daily that his shop will continue selling hairy crabs. Chu said the crabs were not sourced from the two farms in question and had passed all safety tests when they entered Hong Kong. He added that his business was connected to one of the two farms in Jiangsu, but only for the handling of import paperwork.

Li Weihong, director of the publicity department of Jiangsu Entry-Exit Inspection and Quarantine Bureau, said that his bureau and the Jiangsu Ocean and Fisheries Bureau were investigating the two farms.

"We have suspended the inspection and quarantine of the two companies' products. And hairy crab samples farmed at the two companies have been sent to authorized agencies for further and detailed examination," Li said.

Thus far, all tests of the farms' crabs met the food safety standards of the related departments in Hong Kong, according to Li.

Shadow Li and Dara Wang contributed to this story.

Contact the writers at willa@chinadailyhk.com