The family of Noelle Martin are concerned about her safety. Photo/Supplied
Waikato police have "serious concerns" for the safety of a Hamilton teenager who hasn't been seen for three days.
Noelle Martin, who turned 18 on Christmas Day, was last seen about 5pm on Thursday at a Fairfield property.
Police say she hasn't contacted family or friends since and it was "very out of character for her".
It is unknown what she was last wearing.
Her cellphone last polled on the 19th of January in Manukau, Auckland.
Noelle Martin's sister, Mandeno Martin, posted on Facebook that there had been a potential sighting of her in Ashley Ave, Mangere, with a man described as being 5'10 (178cm) or 5'11 in his early 20s.
He was "possibly Maori with short, dark hair, slim build between 85-90kg.
Mandeno Martin said the family had received a lot of feedback from the public so far, including the sighting of her sister at a phone booth on Ashley Ave, but were baffled as to why she would be in Auckland.
"I got a call from a stranger who said he said hello to her while getting something from a shop and it wasn't until he got home and saw the post [on Facebook] from his friend that he recognised her because of her hair ... so he rang me.
"She was with a man but we don't know who the man is and we have no contacts in Auckland and we don't know of any friends in Auckland."
They now had to face the possibility the pair were travelling between Hamilton and Auckland.
Martin said it was even more strange for her to disappear now as she was due to start an engineering apprenticeship in the city tomorrow.
Anyone with information is urged to phone Hamilton police on 07 8586 200.
Police said the explosive - believed to be an old grenade - has been taken away.