Soured noodles were to blame for the nitrite food poisoning accident which happened a week ago at aprimary school in Haikou, capital of south China's island province of Hainan, a local offic ial said on Thursday.

One pupil is still in hospital receiving further treatment but all the other 28 diagnosed with food poisoning have been discharged, Huang Xingguang, mayor of Haikou, said at a press conference.

The children, aged from 6 to 10, are from Changmao Primary School in Haikou, and they fell sick at around 2 PM on February 16 after having noodles for lunch at the school canteen.

About 600 children had lunch at the canteen and later some of them showed symptoms of vomiting, abdominal distension, stomach pain and dizziness. A total of 35 pupils were sent to hospital forfears of food poisoning.

Tests showed that the children were poisoned by nitrite, which is usually found in pickled food. However, the school canteen workers denied they provided pickled food for lunch.

Investigations showed that the canteen used noodles left over from breakfast and the noodles were found to "have gone bad," according to Huang.

The local educational authorities have issued a warning to the primary school and have handed out punishments to the relevant people who were responsible for the accident, Huang said.

(Xinhua News Agency February 24, 2004)