Maruha Nichiro Holdings, a supplier of frozen food such as frozen pizzas and chicken nuggets, recalled up to 6.3m packages allegedly tainted with pesticide in Japan last month.
The total number of people who have reportedly become ill after eating frozen food with possible pesticide malathion, a chemical used to kill aphids in corn and rice fields, is under scrutiny.
The recall was triggered after members of the public complained that one of its frozen pizzas smelled of petroleum oil or machine oil.
The health ministry confirmed 556 people suffering symptoms after eating those products last week. But estimates of the number of people who are sick vary.
Public broadcaster NHK said Wednesday 1,700 people became ill after eating the Maruha products, while Kyodo News agency put the number at 1,400. Prior to that, NHK said the local government announced 356 people were affected.
Both reports said it was unclear whether consumption of the tainted products was directly responsible for the illnesses, which may have caused public hysteria and the health ministry reported no detected malathion in nearly three dozen cases tested.
Maruha Nichiro Holdings used full-page ads in major newspapers last week apologizing and warning consumers not to eat any of the food, including pizza, croquettes and pancakes manufactured at a factory in Gunma Prefecture, north of Tokyo.
"The products will have a strong smell and eating them may cause vomiting and stomach pain," it said in a statement, alongside 51 colour photos of the products.
Maruha Nichiro said it had so far retrieved about 1.1m packages.
Malathion has relatively low toxicity levels for humans, but exposure and ingestion can cause diarrhea and nausea.
Maruha Nichiro Holdings is one of the nation’s largest seafood processing companies.