An Auckland mum has posted a warning on Facebook after an early morning visit left her feeling "shattered" and fearing for her family's safety.

She heard a light knocking at her front door at 4am this morning and found a woman asking to be let in.

Fearing that the visitor was not acting alone, she did not agree to the request and told the woman to leave the property before calling the police.

The mother-of-three from Beach Haven on Auckland's North Shore posted the tale on a Facebook community group, urging others to look out for the woman: "4am this morning we had a girl lightly knock three times at our door.

"She said 'let me in I need some help', she was very clearly not distressed. Normally I would but I've seen posts where there's a male waiting outside.

Be warned, don't let her in. Called police straight away who have come and are out looking. Not a nice thing to happen when you have three children in the house."

The woman told the Herald she was "just shattered" after the incident and described what happened during the chilling encounter.

"My front door has glass panels, I heard a faint knock after settling Bubs, then I heard it again, so went to the other end of the house and there was no one at the front door," she said.

"I pulled the handle down to make sure it was locked, turned around to walk away and she knocked again, I turned back around and she was standing there."

The woman, whose three young children and husband were sleeping in the house, then confronted the woman.

I said to her 'what do you want?' She just said 'let me in, I need some help'. I yelled and told her I'm not letting you in go away or I'll call the cops. She left fast."

Other Beach Haven residents thanked her for the warning, saying that thieves were getting "more and more brazen".

Others described similar instances of strangers coming to the door and asking for people who did not live at the house.

Some questioned if the woman really needed help and asked if the young mum should have opened the door.

She responded that she couldn't "take that chance" and that there was "no urgency in her voice at all".

One woman shared her own story of fleeing domestic violence, saying that she had been forced to run to strangers' houses at "ungodly hours", before agreeing that she "probably wouldn't open the door either".

A Police spokesperson confirmed that they attended the incident and checked the nearby area for the unknown woman, but were unable to locate her.

They said: "Police acknowledge the member of the public did the right thing by calling Police. We encourage anyone who at any point feels unsafe or sees anything suspicious to call 111. Police are not immediately aware of any similar incidents in the area."

Police recommend people follow this advice to keep their homes secure and suggested remembering these key points:

• Don't open the door to strangers. Install a peephole in your door. If you don't know someone, keep the door closed.
• Have a phone by your bed.
• Arrange with a neighbour to phone or visit you if your curtains are still drawn after a certain time in the morning.
• Never tell someone that you are alone in the house.
• Install a wide-angle door viewer so you can see who is at your door.
• Keep your doors and windows secure and close your curtains at night.
• Invest in good-quality, secure locks.