Grilled eel, a popular summer delicacy in Japan, is behind a department store food poisoning incident that has left more than 140 people sick and one dead, the store's president said.

Shinji Kaneko of Keikyu Department Store in Yokohama -- about an hour from Tokyo -- apologised after the customers, who last week bought lunch boxes containing eel, suffered vomiting and diarrhoea.

One of the customers -- reportedly a woman in her 90s -- died, Shinji Kaneko told reporters on Monday, bowing deeply and offering "our most sincere condolences".

The products included eel cooked in the traditional "kabayaki" style: skewered, grilled and basted in a sweet, sticky mixture of soy sauce and mirin rice wine.

Consumed worldwide, eel is particularly popular in Asia, and remains found in Japanese tombs show it has been eaten on the archipelago for thousands of years.

A probe by health officials detected a type of bacteria called staphylococcus aureus in the products, Keikyu Department Store said.

"We take what happened very seriously and feel deeply sorry about it. We will fully cooperate with investigations by public health authorities," Kaneko said. 

Tokyo-based restaurant Isesada, which operates a stand inside the Keikyu department store, was responsible for cooking and directly selling the eel products.