Mum's clever trick to keep her 7-yo daughter safe from online strangers goes viral.

A mother’s trick to keep her seven-year-old daughter safe online has gone viral.

Sue Taher came up with the idea of an official government letter warning after her “adorable innocent daughter” confessed to breaking the house rules of chatting to strangers online.

“She begged me to ground her as she was wrong and so sorry for breaking the house rules,” Taher posted on Facebook.

The mother of two tossed up between confiscating her daughter’s iPad and grounding her but came up with one better.

The Sydney mum told Mamamia she decided to pen a fake letter with an official looking government letterhead addressed to Mr and Mrs Taher because her twins were interested in politics.

The letter said their daughter “had been found guilty of chatting online with strangers” and instructed that the internet would be cut off for her safety until further notice.

"The letter is just a reminder, deterrence and will possibly freak the crap out of her for a few years  - I hope," she said on Facebook.

"The response when I gave her and her brother the letter was exactly what I was aiming for.

"The letter doesn't replace continuous education about cyber danger and stranger danger and keeping the open dialogue and honesty with your children."

Taher says her daughter is a bright and tech savvy seven-year-old so grounding her wasn't going to make her realise it was a serious matter.

"I know it's not everyone's parenting style and some people have said I'm deceiving my children but I figured we all survived the Easter bunny, tooth fairy and Santa white fibs," said Taher.

Taher said her aim was to ensure her daughter's safety and spread the message to parents that children are not safe online even on online games and apps specifically for children.

"My whole rationale behind the letter is to protect her innocence as long as I can and express stranger danger even in tailor made apps for children."

Hundreds of people have commented and over 1,000 people have liked the Sydney mum's post on the Facebook page, Love What Matters.

Podcast: The terrifying text slang of teens.