The calls come amid growing fears over the distribution of eggs contaminated with insecticides, which experts say could harm human kidneys and liver if consumed in large quantities.

So far, the 52 poultry farms have been revealed to have sold eggs tainted with high levels of insecticides.

The farms had used eight kinds of pesticides including fipronil and flufenoxuron, which are used to kill fleas, lice and ticks on animals, according to the government’s inspection.

About 1370 farms, or 94 percent of the poultry farms in the country, use battery cages that severely restrict animals’ movements and pose hygiene issues, according to government data. The floor area of a cage for each bird is about the size of a sheet of A4 paper.

South Korea is not alone. Eggs containing insecticide fipronil were found in the food chain in 16 European countries and Hong Kong in August, according to the European Commission.

The animal rights activists highlighted that the egg scare could have been prevented if chickens had been able to freely move around and remove ticks by cleaning themselves with sand and soil.

“As five to six chickens are locked in a battery cage, their immune system weakens and diseases spread in no time. As there are no ways to get rid of ticks, farmers cannot help but spray insecticides. In such an environment, the tainted egg crisis and the outbreak of bird flu is just a natural consequence,” activists said.

Intensive farming is also to blame for the outbreak and spread of the bird flu virus, they said.

Until April, nearly 40 million poultry were culled due to bird flu, which was first reported in November last year. When bird flu infects a single bird on a chicken farm, the whole population is destroyed to stop the spread.

The government said it would tighten regulations on the use of insecticides and ensure codes are printed on eggshells to inform consumers of when and who produced the eggs. In the long term, it will expand a system to certify eco-friendly farms with high animal welfare standards, it said.

But animal welfare groups said it is not possible under the current system that lacks a comprehensive animal welfare policy and government body in charge of it.

“To push for the reforms, a team currently in charge of animal welfare under the Agriculture Ministry should be expanded so that it can effectively improve animal welfare standards in the face of the livestock industry’s pursuit of their own interests,” they said.

The government has received criticism for its poor response to the egg contamination scare -- including its failure to carry out a thorough inspection and lack of coordination among relevant government bodies.

President Moon Jae-in apologized Monday over the scandal, vowing measures to improve the livestock farming environment.

“In the wake of this case, we have to examine the entire livestock industry’s safety control system and promptly craft measures that can be trusted by citizens,” Moon said at a Cabinet meeting.

By Ock Hyun-ju (laeticia.ock@heraldcorp.com)