Hanoi - Spoiled cakes are the suspected cause of a food poisoning outbreak that put hundreds of students at a Ho Chi Minh City secondary school in hospital this week, health officials said Tuesday.

"Four hundred seventy children were hospitalized due to the food poisoning on Monday," said Le Truong Giang of the Ho Chi Minh Department of Health. "A preliminary investigation shows the cakes the children ate may be the cause."

The children were sent to Ho Chi Minh City hospitals Monday afternoon, a few hours after eating a school lunch of fried squid, cakes and milk.

They were suffering from headaches, nausea, vomiting and diarrhoea, according to Dr Nguyen Thi Thanh Minh of Ho Chi Minh Children's Hospital Number 2.

No deaths were reported, but over 400 of the patients remained in hospital Tuesday.

Giang said that authorities had ensured proper hygiene at the school's kitchen, where the squid was prepared, but that the cakes and milk had come from outside the school.

A total of 5,000 cases of food poisoning were reported by Vietnam's Food Hygiene and Safety Agency in the first six months of 2008, including 43 deaths, 15 more than in the same period last year. (dpa)