A total of 251 pupils fell ill after drinking milk at a school in northwest China's Shaanxi Province, said local authorities on Friday.

Sixteen pupils showed signs of illness, including fever, abdominal pain and diarrhea, after drinking the milk provided to the Yuhe Town Central Primary School in Yuyang District, Yulin City, on Wednesday morning, said a spokesman for the district government.

Seventy students were hospitalized for observation and 44 students remained in the outpatient department for observation as of 6 p.m., said a school representative.

But none of the children showed any other abnormal signs after a day's cure, according to a local government spokesman late Friday night.

The milk was purchased by the district's education bureau and then distributed to the students every morning, said the representative.

There was plain milk, yogurt and milk with walnut flavor. The 16 students with signs of poisoning all had plain milk, said the representative.

The school's milk inventory has been sealed off. The milk's producer has arrived to assist in the on-going investigation.