The “administrator” of the sick “Blue Whale” suicide game has been traced by police back to a Moscow postman. And he allegedly had more than 30 schoolgirls under his spell.

Ilya Sidorov, 26, reportedly has confessed to conceiving and creating the social media game that gave youths a series of increasingly risky dares — ending in their own suicides.

Police questioned Sidorov over allegedly instructing a 13-year-old girl in the remote village of Yetkul to jump under a passenger train.

The girl had been taken to a hospital with cuts from an attempted suicide. Previously, he allegedly tasked her with outlining a blue whale on her arm and inflicting self-harm.

Sidorov allegedly broke down under interrogation, admitting to “administrating” a broader online “Blue Whale” challenge.

Sidorov has since been detained and extradited to Chelyabinsk in the Urals, where he faces charges relating to inciting the schoolgirl’s death.

A police spokeswoman said mobile phones, a tablet computer and several SIM cards have been seized as evidence.

“The suspect clarified that he is the administrator of a so-called suicide group that had 32 members, all of them underage,” the spokeswoman said. “He assigned them tasks aimed at injuring themselves in order to incite suicide.”

But Sidorov is not the only suicide-game “administrator” to have been arrested.

Philipp Budeikin, 21, is also being held by Russian police, charged with coaxing up to 16 schoolgirls to kill themselves.

The suicide game got its name from the way whales appear to beach themselves deliberately.

Its popularity has spread beyond the bounds of Russia, with related suicide attempts being reported in Spain, Portugal, France and Britain.