Iranian authorities have blamed a murky social-media challenge known as Blue Whale for suicide leaps by two teenaged girls, throwing the spotlight on an online phenomenon that has been tentatively linked to suicides around the world but remains clouded in mystery.

In the first reported incident of its kind in Iran, police said the two young women jumped from a bridge in the central city of Isfahan on October 21, leaving one dead and the other hospitalized in critical condition.

Some Iranian politicians have responded to the Blue Whale report with calls to further bolster the authorities' control over the Internet, which is already heavily filtered by Iran's clerically dominated government and its censors.

Mehdi Masoom Beigi, the police chief of Isfahan, said the authorities discovered an audio message purportedly recorded by the girls in which they bid goodbye to their parents and revealed they would take their lives to complete the Blue Whale game, according to Mizan Online, the judiciary news agency.

The Blue Whale game, also known as the Blue Whale Challenge, involves an anonymous "master" assigning various acts of self-harm to a participant over a period of 50 days. The tasks are said to become increasingly dangerous, from watching horror movies to acts of self-mutilation. On the final day, participants are encouraged to complete the game by committing suicide. Users are encouraged to post photos of their daily challenges online.

Scores of suicides and attempted suicides have been provisionally linked to the game, although on closer inspection none of them has been found to have a conclusive tie.

The name is a reference to the way whales sometimes intentionally beach themselves and die.

'Satanic Ideas'

Iran's communications and information-technology minister, Azari Jahromi, said on Instagram on October 22 that the incident was "shocking" and urged more parental supervision over teenagers' use of social media.

In September, Jahromi said Blue Whale was inspired by "satanic ideas" and vowed his ministry would try to prevent its penetration in Iran by tightening its grip over the Internet.

In recent years, the Islamic republic has blocked access to YouTube and Western social networks such as Facebook and Twitter. That has led Iranian authorities to create one of the largest Internet filters in the world, although its citizens continue to access Western websites through tools like virtual private networks (VPNs), on which the authorities have clamped down.

The October 21 incident has prompted an outpouring of concern among Iranian social-media users.

"On Stage 26 of the Blue Whale game you are told: 'We will contact you to announce the time of your death. You have to accept it.' Let's take care of our teenagers," Iranian filmmaker Ghazale Soltani tweeted on October 22.

Russian Origins?

Blue Whale appears to have started on VKontakte, a social-networking site widely used in Russia.

In a much-criticized article published in May, Russian newspaper Novaya Gazeta claimed that the "vast majority" of the roughly 130 youth suicides in Russia between November and April 2016 were tied to Blue Whale.

Subsequent reports have debunked that assertion, and law enforcement and other experts have expressed caution over ascribing any deaths to the game.

Many Russian activists have argued for a greater focus on the factors that drive young people's interest in such games, while many politicians have argued the phenomenon should lead to more online restrictions.