Tara Hipwell has not been seen since she left San Clemente High School in Mayfield, a north-western suburb of Newcastle, about 3.20pm last Thursday.

She did not arrive at her Waratah home that day, and police say they hold serious concerns for her welfare due to her young age and the length of time she has been missing.

Inspector Michael Gorman, from the Newcastle Local Area Command, said police were investigating Tara's online activities, including her presence on dating websites, in the days before she vanished.

Tara was posing as a 19-year-old woman on a number of dating websites seen by Fairfax Media.

On one website, Tara's profile says she did not complete high school nor have any children. However, she lists an extensive list of pets, including cats, dogs, fish, rabbits and rodents.

On another dating website, she writes: "I love the colour purple. I don't drive or work.

"My favorite [sic] books are crime and romance books. I am really good at talking and laughing."

She writes that she is looking for men aged 18-25 who are available for long-term dating.

Police are investigating whether Tara had arranged to meet any men she had been chatting to online.

"We are certainly looking at the social media aspect of it," Inspector Gorman said.

"While Tara is only 14 years of age, she does look older than that, as some teenage girls do, and part of our concern is that she has been in contact with people who are quite a deal older than her."

Tara has disappeared from her home previously but was found within a day, police said.

Tara's family, including her brother Brett, were handing out leaflets at Stockland Jesmond Shopping Centre on Wednesday, after someone reported seeing her there in the company of a man this week.

Another person reported seeing her at Marks Point in Lake Macquarie over the weekend.

Inspector Gorman said police were following up a number of reported sightings of Tara from as far away as Singleton and Branxton.

The mother of one of Tara's friends appealed for the teenager to let someone know she was OK.

"Tara if you are reading this please contact someone so many people are worried about you," she wrote.

Police described Tara as being 178 centimetres tall, with a medium build, light brown hair and blue eyes. She has braces on her teeth.

Anyone who knows where Tara is has been urged to contact Waratah police station on 02 4926 6599 or Newcastle police station on 02 4929 0999.