MOSCOW, Russia (CNN) -- Members of a doomsday cult are refusing to leave their hideout in a cave in southern Russia in spite of intervention from their leader, a government official said Friday, adding pressure to a stand-off with the authorities that one side believes will only end with the apocalypse.
The cult, which calls itself the "true Russian Orthodox Church," believes the world will end in May.
The cult members - including four children - holed up in a ravine in Russia's Penza region, around 400 miles southeast of Moscow, have threatened mass suicide if the authorities try to intervene, the official said.
The 29 members of the cult, which calls itself the "True Russian Orthodox Church", claim they will ignite gasoline canisters if authorities try to force them out, regional administration spokesman Yevgeny Guseynov told CNN.
The cult excavated the cave system themselves after their leader, Father Pyotr Kuznetsov, told his followers to hide themselves away to await the end of the world, which he predicted will take place next May, according to Russian media reports. Watch a cult expert discuss the standoff »
With efforts to persuade the cult members to leave the cave so far proving futile, authorities have enlisted the 43-year-old leader to try to get them out.
Although the cult members are exchanging letters with Kuznetsov, they are mistrustful of his intervention because they believe he is acting under the influence of the Russian government, Guseynov said.
"They still respect him, they listen to him but they don't trust him as they believe he is acting under pressure from the authorities", Guseynov said.
The cave dwellers are also refusing to speak to Russian Orthodox priests brought in to negotiate, he said.
Kuznetsov was charged Thursday with setting up a religious organization associated with violence. He has been undergoing psychiatric exams since his arrest.
"I've met the man, and he's definitely mentally sick, big time," Guseynov told CNN.
A trained engineer, Kuznetsov did not let his followers watch television, listen to the radio or handle money, according to Russian media reports.
Among the children inside the cave is an 18-month-old baby, reported Itar-Tass, the Russian news agency. Temperatures in the cave are below 54 degrees Fahrenheit (12 degrees Celsius), the Russian news agency reported.
The cult members have gathered enough food supplies to last until Spring, according to the agency.
A 24-hour operation has been established in the nearby village of Nikolskoye incorporating teams of local police, officers from the Russian Ministry for Emergency Situations and medical staff.
Guseinov said specially-trained negotiators have arrived on the scene to talk with the cult members.
The negotiators are trying to persuade them to accept food, medicine and hot water to bathe the children, he said.
Guseynov said there were no plans to use force to end the stand-off, which began on Thursday and Friday last week.
"Any special operation that involves the use of force against those people is totally out of the question", he said. "If they do come out of the cave, it would be only if they choose to do so voluntary." CNN's Maxim Tkachenko in Moscow contributed to this report. E-mail to a friend
CNN's Maxim Tkachenko contributed to this report.