Thailand - The Mental Health Department (MHD) has urged parents to closely monitor their children's online activities, especially in the wake of scary "Momo Challenge" reports.
The Momo Challenge, dismissed by many as a viral hoax, is a cause of concern because, if the reports are true, young people are vulnerable to being badly hurt or even killed.
Several reports suggest Momo, which is associated with a grotesque bird, has sneaked into YouTube and its YouTube Kids platform and coerced young watchers to take up risky, potentially deadly challenges.
According to these reports, some children have been challenged to open an oven by themselves, take whatever pills they could find and slit their wrists. Some challenges reportedly involve harming others.
The reports have caused alarm across the world.
"I've heard that Momo managed to sneak in because its creator hid it between cartoons to evade security detection," MHD director-general Dr Kiattibhoom Vongrachit said recently.
He said the disguised nature of the Momo Challenge clips could help it evade the watchful eyes of parents.
"Parents should closely monitor their children, particularly younger ones, when they use online media," Kiattibhoom warned.
He said if Momo Challenges really exist, they could cause fear, worry and stress among young victims.
"Victims could fall into depression and end up harming themselves," he said.
Kiattibhoom's advice is that parents talk to their children often to learn what they have encountered online.
"If your kids have already run into a Momo Challenge, heart-to-heart talks, advice and close monitoring will be necessary," he said.
He added that if children showed signs of severe stress, counselling was possible through the mental health hotline or any public-health office.
According to Forbes magazine contributor Andy Robertson, there is no evidence of direct harm being caused by the Momo Challenge. It is essentially a viral "ghost story", in his view.
Rather than sharing warnings about the challenge, he recommended focusing on giving children good positive advice, setting up technology appropriately and taking an interest in their online interactions.
The BBC has reported that YouTube plans to disable users' ability to leave comments on almost all videos featuring under-18s over the next several months in an attempt to "better protect children and families".
The report did not connect the move to the Momo Challenge, but pointed out that there were concerns over obscene and sexually inappropriate comments.