The pupils, all from the Pengdian Central Primary School in the Cangxi County of Sichuan, have developed symptoms of fever, headache, stomachache and diarrhea, some of them suffered from nausea and vomiting, according to Huang Tingquan, vice head of the county, who noted that the test result shall come out tomorrow.

The 23 hospitalized students are in stable condition, but they have to continue medical treatment for several days, said local sources.

The first case was reported on Thursday afternoon and there are no similar cases reported outside the school.

The Pengdian Central Primary School located in the mountainous area 90 kilometers away from the county government. Among all its 780 students, 621 live on campus, including all the 92 sickened.

The Cangxi government has embarked a daily case reporting system, gave all other students and staffs in the school preventive medicines and ordered a thorough disinfection in the school's dinning hall.

Earlier this week, food poisoning has killed one girl and sickened another 459 students in Chinese provinces of Heilongjiang, Shaanxi and Hubei.