NANJING: Police have arrested a snack bar owner who confessed to spreading lethal rat poison into the food of his business rival on Saturday morning, killing 38 people and leaving hundreds seriously ill.

A resident in Qiaolin Town in Nanjing's Pukou District, Chen Zhengping, was arrested on Sunday morning aboard a train in Zhengzhou in Central China's Henan Province, 550 kilometres northwest of Nanjing.

He was taken back to Nanjing for questioning where he confessed to the crime.

Chen said he was jealous and hated his business competitor, so he put a banned rat poison into the food prepared by the Zhengwu Pastry Bar, which supplies the Heshengyuan Soybean Milk Shop in Tangshan, in Nanjing.

The Heshengyuan Soybean Milk Shop, where the victims bought the poisoned food, was a designated shop for the Zuochang Middle School, an army unit and a construction site.

Most of the victims were in stable condition at civil and army hospitals. Six patients were still in a critical condition.

Most of them were middle school students and construction workers. Some local residents and a dozen soldiers were also among the poisoned.

After urgent treatment and meticulous care, some of the victims have already been discharged from hospital, but more than 400 are still hospitalized for further treatment, hospital sources said.

It is possible that some of those poisoned might not survive, although the majority are now showing signs of recovery, said a doctor who only gave his surname as Hu.

The lethal poison, commonly known as Dushuqiang, (tetramethylene disulfotetra-mine), has been banned in China for its possible dangers to people and livestock.

"The doctors and families of the victims are mostly concerned about the after effects of the rat poison which might leave the victims paralyzed or mentally retarded in the future," said a doctor at an army hospital.

The Nanjing health department has issued an emergency notice calling for all catering businesses to undergo self-examination of hygiene conditions to ensure food safety during the coming Mid-Autumn Festival and National Day holidays.

In another development, the provincial hygiene supervision station issued an emergency notice forbidding all food production companies and food sales companies to use deadly poisonous chemicals including tetramethylene disulfote-tramine to kill insects and rats.

An inspection on the issue is expected to be conducted soon, the Nanjing-based Yangzi Evening News reported.

Xinhua contributed to the story