The Qolsharif Mosque in Kazan, Russia Wiki Commons

Four members of a Muslim sect in Russia's Tatarstan region have been charged with cruelty against children, after the authorities discovered last week 70 members living in catacomb-like cells in an eight-level underground bunker on the outskirts of the city of Kazan, under the orders of a self-proclaimed Islamic prophet Fayzrahman Satarov.

The sect's founder, 83-year-old Satarov, who claims to be the last Muslim prophet, ordered his followers to live in catacombs, which they dug themselves at least a decade ago. The followers have been living underground since, isolated from the outside world, with no access to healthcare, education or even sunlight and proper ventilation, Reuters reported.

The members of the group, known as the Fayzrahmanist sect, included 20 children, many of them were born underground and had never known the outside world until the authorities freed them on Aug. 1. The sect was uncovered during an investigation into recent attacks on Muslim clerics in Tatarstan. Extremist literature was found in the compound, according to an RT report.

The cells were built under an old, three-storey brick house on a 700 sq m (7,530 sq ft) plot of land, according to an Associated Press report.

The youngest among the children was 18 months old. All the inmates have been sent for health checks. A 17-year-old girl was reportedly pregnant.

Satarov, who is believed to be a former deputy of a Sunni Islamic cleric in the 1970s, has been charged with the crime of "arbitrariness," which covers "actions contrary to the order presented by a law." The sect reportedly denounces Russian state law or the mainstream Muslim leaders in the region.

In a 2008 interview with the Komsomolskaya Pravda daily, Satarov said he denounced Islamic clerics and authorities in the Communist era when he said the KGB sent him to Muslim nations with religious freedom, while the Soviet Union was suppressing religion.

Prosecutors have initiated a criminal inquiry and said the sect will be dissolved if it continues the illegal activities. The authorities will also investigate suspicions of whether the children were abused in other ways besides depriving them of basic rights.

The children will temporarily live in an orphanage, said pediatrician Tatyana Moroz. "They looked nourished but dirty, so we had to wash them," she said in televised remarks.

The reports said only a court can decide whether to allow the children to stay with their parents. The parents have expressed concern about their children's medical treatment.

Satarov's house was raided last week as part of an investigation into the killings of two clerics who were critical of the puritanical Islamist groups known as the Salafis.