HOHHOT -- The last batch of 76 students who suffered from food poisoning at a secondary school in north China's Inner Mongolia Autonomous Region in late September has been discharged from hospital, the local educational department said on Saturday.

"So far, all the 217 sickened students have recovered and we had received no new case of food poisoning by Friday," said an official with the educational department in Fengzheng City, where the food poisoning happened.

The students at the Fengzhen City Experimental Middle School developed symptoms of dizziness, headache, fever, vomiting and diarrhea on September 28 after dining at the school canteen.

Investigation shows that food prepared for the students on September 27 was mixed with leftovers which had already turned bad.

Local police have detained seven administrative workers at the canteen. The city government has suspended school principal, Suo Jianmin, who may face further disciplinary action.

Fengzhen is more than a three-hour bus ride from Hohhot, the regional capital.