Warning: This article contains graphic content which may disturb some people.
New Zealand police and the Mental Health Foundation are warning people to keep an eye on each other, after reports the 'Blue Whale' challenge has come to New Zealand.
The challenge has gained notoriety worldwide after it was reportedly linked to a cluster of suicides in Russia earlier this year.
It gets participants to complete daily tasks for 50 days, ranging from watching horror movies to harming themselves.
According to media reports, on the final day participants are urged to kill themselves.
New Zealand police warn it's a "particularly nasty" app and a timely reminder for people to keep an eye on what young people are doing on their phones.
"I have had a quick look in the Apple appstore this morning and can't seem to find it, which is a good thing!" Waikato District Police wrote on Facebook.
"In saying that though, if it does somehow seem to find it onto your young person's phone we would recommend deleting it straight away."
The warning has been echoed by the Mental Health Foundation, which added it's not yet aware of any young people in New Zealand taking part in the challenge.
"Parents and guardians concerned their children may be aware of or taking part in the challenge should support their children to share any concerns or worries they may have," it said.
"Young people can sometimes find peer pressure difficult to cope with - parents and others can help by talking over different ways of saying no to things that make young people feel uncomfortable or scared. Open conversations and guidance around safe internet use can help to protect and support young people."
The Mental Health Foundation said people should keep an eye on others and help them if necessary, a sentiment echoed by police.
"Hopefully this app disappears and blue whales can go back to being the majestic creature of the deep that they were intended to be," Waikato police said.
If you or someone you know is in crisis and needs immediate help, call Lifeline on 0800 543 354 or the Suicide Prevention Helpline on 0508 828 865.