A Japanese drugmaker whose dietary supplements are at the centre of a growing health scare reported on Thursday two more deaths potentially related to its tablets.

Last week, Kobayashi Pharmaceutical recalled three supplement brands -- "Beni Koji Choleste Help" and two other products -- which contain an ingredient called red yeast rice, or "beni koji", supposed to help lower cholesterol.

Thursday's announcement brings the total number of deaths under investigation by the company and health ministry to four, with more than 100 other people hospitalised.

"We were told yesterday by a bereaved family that a person who had been using Choleste Help had passed away due to kidney disease," the drugmaker said in a statement Thursday.

It added that it had been told separately that another person who had used Choleste Help in recent years had died.

"We are in the process of confirming the facts and causal relationships in both of these cases. However, we decided to make this report public from the viewpoint of prompt disclosure."

The Osaka-based company says it has also supplied red yeast rice to around 50 other firms in Japan and two in Taiwan.

Kobayashi Pharmaceutical sells a wide range of health products marketed through television adverts in Japan.

Medical studies describe red yeast rice as an alternative to statins for lowering high cholesterol, but also warn of a risk of organ damage depending on its chemical make-up.

Dozens of Japanese firms that used the beni koji provided by Kobayashi Pharmaceutical have also separately announced recalls.

The affected products include various health tablets, as well as a rose-coloured sparkling sake, salad dressing, bread and miso paste used in many traditional dishes.