A total of 29 sect members, including four children, of the so-called True Russian Orthodox church have moved into the shelter, which contains underground wells, a kitchen, monastic cells and other facilities. They wrote a letter to local authorities saying they had gone underground of their own free will.
"The inhabitants of the underground shelter have threatened to set themselves on fire if forced out," Alevtina Volchkova said, adding that a criminal investigation has been launched against the sect leader, who calls himself Father Pyotr.
He is likely to undergo a psychiatric examination and will face up to three years in prison if found guilty of infringement of his followers' rights. The prosecutor also said all the cult members are from other Russian regions or former Soviet countries, and some have breached Russian laws.
When policemen and local priests tried to persuade them to leave they threatened to blow themselves up, as they have a plenty of explosive materials, such as bottled gas and kerosene.
"It was God who told us to act this way, and a book about us is being written in heaven," a popular Russian tabloid Komsomolskaya Pravda quotes a cult follower as saying.
The tabloid also said the sect was established about two years ago by 43 year-old local, Pyotr Kuznetsov, who set up a prayer house in the village.
"They [sect members] don't work and stop their children from going to school," the newspaper quotes a local resident as saying.
Several months ago, a message saying that "sorry, we have made a vow of silence" appeared on their church doors and Kuznetsov announced the advent of the apocalypse. When their shelter was completed the cult followers moved in.
"A microbiologist doctor is among them and the temperature inside is 12-17 degrees Celsius (53-62 Fahrenheit)," - Volchkova said.