Police have received a number of complaints about a smartphone app which allegedly encourages young people to self-harm.

Waikato Police have posted a warning on their Facebook page after receiving a couple of reports of a new smartphone app called "Blue Whale".

'Without getting into the nitty gritty, the app is particularly nasty as it targets young people and encourages them to complete self-harm challenges and eventually suicide,” reads the Facebook post.

'It has apparently been a bit of an issue overseas. I have had a quick look in the Apple Appstore this morning and can't seem to find it, which is a good thing!

'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.

Police say it's a timely reminder to monitor what your young folk are looking at on their phones.

'And on that note, if you or anyone you know are struggling with self-harm or thoughts of suicide, please give either us or another agency a call to talk through it. I've listed a few numbers below.

'Hopefully this app disappears and blue whales can go back to being the majestic creature of the deep that they were intended to be.”

Numbers to call if you need to talked with someone

Lifeline: 0800 543 354

Suicide Crisis Helpline: 0508 828 865 / 0508

Youthline: 0800 376 633 or free text 234, or email talk@youthline.co.nz

Kidsline (ages 5-18): 0800 543 754