A total of 45 children aged two to seven have been hospitalized, and another 21 are receiving outpatient treatment.
A preliminary probe revealed that a single businessman supplied food to all the kindergartens affected, although it is unclear whether his products were the source of the outbreak.
The incident follows a number of food poisoning outbreaks at summer camps throughout Russia.
About 120 children and adults were infected with an intestinal bug in the Novgorod Region in northwestern Russia Wednesday.
About 40 people, including 33 children, were hospitalized with an acute intestinal infection in the Sverdlovsk Region, in the Urals, June 28, while dysentery led to the hospitalization of 93 children and two adults at two summer camps in the Moscow Region the same month.
