Beach skeleton a teenager or young woman - police

The skeletal remains were found on Sunset Beach in Port Waikato on Saturday morning. Photo / Janna Dixon

A skeleton discovered at a Port Waikato beach is likely to be that of a teenage girl or a woman in her 20s - one of 30 on a missing persons' register, police say.

An autopsy completed at an Auckland mortuary yesterday on a skeleton found at Sunset Beach about an hour south of Auckland revealed the remains were those of a young woman who was buried on the eroding sandhill more than 10 years ago.

The officer in charge of the case, Detective Inspector Mark Gutry of Counties Manukau police, said an on-site investigation had been completed, but it was still not known how the woman had died.

"At this stage we don't have a cause of death and we will have to complete further investigations around the bones of the body to see what we can find," he said.

The intact skeletal remains were discovered by a woman who was out for a beach walk with her dog on Saturday morning.

The dog began digging at a spot about 200m north of the surf rescue tower and unearthed a skull.

Mr Gutry said the death was suspicious and police were "certainly looking at the fact that this body was buried".

But he could not say at this stage if police were investigating a murder.

Given how long the remains had been at the beach and the likely age of the woman, police have narrowed a missing persons' register containing the names of more than 100 people to "about 30".

"We will be working our way through this missing person's list and our main priority is to identify who this body might be and we will continue our investigation from there."