Children spent 11 days playing with the remains of what they thought was a crocodile in a creek before a parent discovered that the body was human, it emerged yesterday.

The children had picked up parts of the badly decomposed body in Stanmore Bay on the Whangaparaoa Peninsula, just north of Auckland.

Police are investigating whether the remains are those of Alanah Brough, 39, missing since January.

The children play for the Hibiscus Coast Raiders Rugby League Club. They found the skeleton during a gala day on July 25, said vice-chairman Merve Heka.

On Wednesday about 6pm, a parent followed his son after the under-9 team's practice to investigate the remains. It is believed he tried to fish them out with a broomstick.

"He pulled it [the skeleton] out and there was black hair on the back of its head still," Mr Heka said. "He dropped it ... He knew straight away it was human. Kids will play with anything they see."

The police were then called.

Mr Heka said a kaumatua would bless the club and creek.

"Three or four of these kids are quite traumatised."

A neighbour said he was walking his dog past the creek on Wednesday night when he spotted about 10 boys prodding the skeleton with sticks.

One told him, "Mister, I think we've found a crocodile in the creek."

"They were in there playing with it for about two weeks ... I didn't know what it was. It could have been lots of things. I thought it might have been a bit of old tree trunk or something."

Ms Brough, mother of boys aged 7 and 14, vanished after leaving her Bonita Ave home on January 30.

Her mother, Judith Brough, said at the time that she had been concerned for her daughter's wellbeing as she had lost weight and been displaying unusual behaviour.

Judith Brough did not want to comment yesterday.

Detective Inspector Bruce Scott of the Waitemata police said it was too early to tell if the body was that of Alanah Brough.

The remains were "very badly decomposed", he said. "Until we have identified the body, we won't know for sure if it is this missing woman.

"She hasn't been sighted since she went missing. This has been an ongoing missing-persons investigation we have been following closely."

Mr Scott said the body appeared to have been in the creek for at least a few weeks and possibly months.

"It appears to have been there for quite some time. It appears to be quite decomposed."

Mr Scott said a pathologist had examined the remains, which would also undergo a formal autopsy.