Fifty-seven people were sick after eating snack food from a shopping center in this capital of northeast China's Heilongjiang Province on Monday, said a health official on Tuesday.

Liu Minglie, deputy director of the city's health bureau, said hospitals in the city had not reported any deaths or any critically ill patients as a result of the poisoning.

He said hospitals have registered 57 people who suffered nausea and vomiting after eating the spicy Chinese snack "malatang" from a vendor in the underground dining area of Hongbo Shopping Center in downtown Harbin's Hongqi Street.

Among those, 28 have since left hospital after they passed medical checks. All of the hospitalized patients are in stable conditions, said Liu.

He said a clinical examination found the patients were poisoned by nitrite.

Lab researches also showed food samples from the hotpot vendor contained excessive amounts of nitrite, the official said without giving exact data on the content.

The stall was closed as authorities conduct an investigation.

(Xinhua News Agency February 24, 2009)