A total of 70 people fell ill after eating at a restaurant in the suburbs of Beijing Friday, police and health authorities said on Saturday.

They suffered nausea and vomiting after finishing a 16-course lunch at the restaurant of Shuian Shanba, a holiday resort in the outer district of Huairou.

Most of the sick were treated at hospitals in Huairou and nine suffering the worst were sent to Chaoyang Hospital in downtown Beijing.

The nine, including a two-year-old boy and his parents, all had clonidine in their blood, a doctor in the hospital's emergency room said on condition of anonymity.

Clonidine is a drug for high blood pressure and is not used very widely in Beijing nowadays, the doctor said.

He assumed the victims' food was probably contaminated with clonidine,

as it was unlikely that dozens would suffer from an overdose of the drug at the same time any other way.

Most of the sick were very drowsy when rushed to the hospital, at least an hour's drive away from Huairou, Friday night, said Dr. Hao Fengtong, a physician with the department of vocational illness and toxicosis.

"Most of them responded little even to my flashlight when I checked their pupils last night," said Dr. Hao.

But on Saturday, the patients all appeared clear-headed but were unwilling to talk to a Xinhua reporter.

Doctors said their conditions were stable. If no complications occur, they will hopefully recover in five to seven days.

The restaurant suspended operation Friday night and police launched an investigation.