A mother-of-three who hasn't been seen since 2002 may be the victim of foul play, police say, as they open a cold case inquiry into her disappearance.

Tuitania (Tui) Marama Barclay, who was aged 29 at the time of she went missing, was last seen in October 2002 when she was living in Dunedin.

She was reported missing by her ex-partner in February 2003, but police found no significant leads as to her whereabouts.

However, they now believe she may have been the victim of something sinister.

Two addresses in Dunedin where Ms Barclay previously lived have been searched, and the police dive squad scoured Ross Creek in mid-April; a place Ms Barclay is known to have frequently visited.

The young mum had previously also gone by the names Tuitania McIntosh, Tuitania Brown and Sandra Williams.

She is described as Caucasian, of petite build and around 180.3cm (5ft 2") in height, with dyed dark brown hair at the time of her disappearance, although her hair was more often blonde in colour.

She had a past history of drug-taking and prostitution, but had been leading a life free of drugs and street-work prior to her disappearance.

Her most recent address in 2002 was in Wakari Road, Dunedin, where she was renting a house with her then partner. The couple had two children together and she also had another child from a previous relationship.

"This appeared to be a woman who had been off the rails a bit in the past but had now turned her life around and showed all the signs of a caring mother who would not leave her three children," said Detective Senior Sergeant Malcolm Inglis, who is leading the cold case investigation.

The decision to re-investigate was based on a "careful re-evaluation and piecing together" of the existing facts, he said.

"As an unsolved missing person case, we've gone back and reviewed this file again. In the interests of ensuring that we've done our best to find out the truth about Tuitania's disappearance, we're re-visiting the inquiry and conducting new investigations," Mr Inglis said.

The investigation team is following a number of leads in its inquiries although it cannot publicly reveal what these are at the moment, he added.

"We are however keen to hear from anybody who might have information that might assist us with this inquiry."

Anyone with information is asked to contact Detective Matt Preece on 03 471-4800, or pass on information anonymously to Crimestoppers on 0800 555 111.

- APNZ