Tokyo: Japanese government health officials on Sunday inspected a factory producing health supplements linked to at least five deaths and the hospitalisation of more than 100 others, one day after the authorities investigated another plant that manufactured the product.

A team of 17 health officials from the central and prefectural governments raided a plant operated by the Kobayashi Pharmaceutical Co's subsidiary in Kinokawa, in the western Japanese prefecture of Wakayama, under the food sanitation act. NHK public television showed the officials walk into the factory.

The Wakayama plant took over the production of the supplements after Kobayashi Pharmaceutical closed another plant in nearby Osaka, which authorities searched on Saturday, NHK said.

Kobayashi Pharmaceutical spokesperson Yuko Tomiyama told reporters that the company is fully cooperating in the investigation. The company says little is known about the exact cause of the sicknesses, which include kidney failure.

The supplements being investigated all used “benikoji,” a kind of red mold, including Kobayashi Pharmaceuticals’ pink pills called Benikoji Choleste Help, which were billed as helping lower cholesterol levels.

The Osaka-based Kobayashi Pharmaceutical said about a million packages were sold over the past three fiscal years. It also sold benikoji to other manufacturers, and some products have been exported. The supplements could be bought at drug stores without a prescription from a doctor.

Reports of health problems surfaced in 2023, although benikoji has been used in various products for years.

The recall came March 22, two months after the company had received official medical reports about the problem. Company president Akihiro Kobayashi has apologised for not having acted sooner.

On Friday, the company said five people had died and 114 people were being treated in hospitals after taking the products.

Japan's health ministry says the supplements could be responsible for the deaths and illnesses, and warned that the number of those affected could grow. The government has ordered a review of the approval system in response to the supplement-related illnesses.

Some analysts blame the recent deregulation initiatives, which simplified and sped up approval for health products to spur economic growth. Deaths from a mass-produced item is rare in Japan, as government checks over consumer products are relatively stringent.