Rewards of $100,000 are being offered for information leading to a conviction in two historic suspected murder cases.
Tanya Farrington and Linda Suzanne Davie both disappeared in suspicious circumstances more than 30 years ago and are presumed by police to have been murdered.
NSW Detective Sergeant Robert George responded to media reports that police were investigating possible links between the girls and notorious criminals including underworld identity John Anderson, serial killer Ivan Milat and New Zealander "Mr Asia" drug syndicate head Terry Clark.
"Any suggestion of those links is just speculation," he told reporters in Sydney on Sunday.
Tanya was 14 when she went missing from her Crows Nest home on Sydney's north shore on March 22, 1979, he said.
She was last seen by her brother watching TV late at night in the family home but was gone when her mother woke up in the morning.
Ms Davie, then 22, has not been seen since she returned to her north shore Wollstonecraft home after visiting her boyfriend in Royal North Shore Hospital on April 6, 1980.
The New Zealander's boyfriend received a letter saying that she would be away until the following week - she was never seen again.
Neither of the women had any reason to deliberately disappear, Det Sgt George said.
"They have not contacted their families in over 30 years," he said.
"We presume that what has happened to them is a result of murder or foul play."
NSW Police Minister Michael Daley said Tanya often snuck out at night and may have hitchhiked to Manly to spend time with friends.
"I'd urge anyone who saw Tanya that night, or might have information about her disappearance to come forward," he told reporters.
Police would also like to speak to Tanya's boyfriend at the time and two men who are believed to have driven Ms Davie and a friend home from Kings Cross on April 5, 1980.
Police are asking anyone with information to call crime stoppers on 1800 333 000.
Pair sought in case of missing model
More than 30 years after budding Kiwi model Linda Davie disappeared from her Sydney home, police have made public images of the men who may be able to solve the mystery.
Australian police say the two men in the computer-generated images were among the last people to see the 22-year-old, but they have never come forward to talk to police.
Miss Davie, from Whakatane, disappeared on April 6, 1980, after visiting her partner in a Sydney hospital. She left only a letter, which her partner received three days later.
The note – which police believed may have been forced – said Miss Davie would be away for a couple of days.
However, when her partner returned to their Sydney home on April 15, the couple's bed had not been slept in and Miss Davie's possessions were untouched.
Miss Davie's case was reopened last year with a A$100,000 reward for information that would solve the cold case.
Detective Sergeant Robert George, of New South Wales, said the images of the two men had been made public in the hope that it might spark someone's memory.
"There's nothing to implicate either male. However, given their involvement with her in the 24 hours leading up to her disappearance, we'd like to speak with them about the night," Mr George said.
Miss Davie met the two men the night before she disappeared, while out with a friend in Kings Cross. The men later gave Miss Davie a ride home.
Searches at the time failed to find the men. These are the first computer-generated pictures of them to be made public.
Stephen Lavender, her partner at the time, urged anyone with information to come forward.
"It's taken a huge amount of time to get this far. It's Linda's time now to get some sort of closure," Mr Lavender said. "It's been 31 years now. We know nothing after all these years. But I bet someone does, somewhere."
Brother Nigel Davie, of Edgecumbe, said anything that could help bring closure for the family was appreciated. "I hope it can help. Anything that can help needs to be out there."
The first man was described as 5ft 10in to 5ft 11in (1.77 metres to 1.8m), 25 years old, of slim build, with a fair complexion, longish hair in a ponytail, hazel eyes and an oval face.
He was wearing a watch and said he was from Melbourne.
The second man was described as 5ft 8in (1.72m) tall, 25 years old, medium build, medium complexion, a rounded face, curly collar-length hair, and a pointed nose. He was wearing a gold-coloured chain and said he was from Sydney. He owned a pale yellow four-door Japanese car, possibly a Datsun.
Police are still working on the case of a second New Zealand woman who went missing from Sydney in similar circumstances in 1980.
Marion Sandford was aged 24 when she left a note at her brother's flat in Sydney's North Shore to say she was with friends and would be gone a few days. She never returned.
Police are considering whether the two cases may be linked.