More than 460 people in the Tver region and neighboring areas are now suffering from the virus, the Interfax news agency said, citing regional health officials.

Denied a Sharp Increase

But Vladislav Ivanov, the head doctor of the district hospital in Rzhev near Tver, denied a sharp increase in the number of new patients.

"We can see that the stabilization has peaked and we expect a decrease in a day or two. We hope for that," Ivanov said in televised comments.

Epidemiologists were centering their investigation on alcohol-free drinks produced by a local brewery, with reports saying lemonade or kvas, a traditional drink made from fermented bread, could be to blame.

Hepatitis A is transmitted through food or water and is often spread due to poor sanitary or personal hygiene practices.