Detectives searching for a vulnerable woman not seen since 1999 are following new lines of inquiry.

Mystery surrounds the disappearance of Margaret Fleming, 36, from Inverkip, after it emerged there is "no record" of her since her last sighting at a family gathering 17 years ago.

Officers have been carrying out a major search since she was reported missing by her two carers - whom with she lived - on Friday, October 28, but have so far drawn a blank and she remains missing.

However, following another appeal for information police say they are "encouraged" by the response from the public and are now following "new lines of inquiry".

They received information from people who believe they have recognised the image of Ms Fleming and are following those up.

Officers will be distributing leaflets on Wednesday to local residents and businesses in the Inverkip and Port Glasgow areas to try and jog people's memories.

Detective chief inspector Paul Livingstone said: "I am heartened by the encouraging response from the appeal for information and we have had a number of people phoning the team to say the remember or recognise Margaret.

"Officers will continue to work to bottom these out as part of the investigation to piece together more detail to Margaret's background.

"We also have officers who will be visible in the local Inverclyde area, delivering leaflets with Margaret's image and engaging with more local people to see if they remember anything.

"Officers continue to search a house and grounds in Inverkip, as well as searching nearby areas. I would continue to ask anyone who may have any piece of information that may help, however small, to get in touch with the investigation team based at Helen Street Police Office, Govan on 101."

A search of their house on Main Road in the Inverclyde town has this week extended into the garden, which is being dug up by officers in the search for any clues.

Detectives from the major investigations team have now joined the probe and officers revealed last month it was an "unusual missing persons case" and Ms Fleming had a "side of her life" which she kept private.

Several items have been removed and examined by detectives who say they will look at every single piece of paper in the property in a bid to gather clues as to Ms Fleming's whereabouts.

STV News understands Inverclyde Council have no record of Ms Fleming since 1999 and there has been no social work or council involvement with her.

The council and the Department for Work and Pensions (DWP) declined to comment on the case but detectives say she has had no contact with local services or any other agencies.

DCI Livingstone said: "Apart from her carers, the last independent sighting of Margaret was in 1999.

"This, along with facts such as having no trace of a job, few friends that are contactable and no evidence of her contact with partner agencies and local services, has led me to become very concerned for her whereabouts and well-being.

"One line of inquiry that I now must consider is the possibility that Margaret may have come to some harm."

Specialist search teams have been sifting through the house where Ms Fleming is believed to live with her two carers to find any documentation, clothing and personal items that could assist in finding her.

Support from expert resources has been enlisted including air support, dive and marine unit, dog unit and search specialists, who have been combing the Inverkip and wider Inverclyde area.

Mr Livingstone added: "It's important that we keep an open mind to all lines of inquiry but the distinct lack of information about Margaret is concerning.

"However, we cannot rule anything out at this point and officers will continue to follow up enquiries about where Margaret has been. I must stress that this is still a missing person investigation.

"Our search will continue from the house into the grounds around it. This is a natural progression in the inquiry to assist our investigation to find Margaret."

Police have appealed for anyone with information to contact them.

Mr Livingstone said: "As this goes on, I am still appealing to anyone who may have information about Margaret to help us build a more accurate picture of where she has been and with whom she has been associating over the past 20 years.

"If anyone remembers Margaret from James Watt College in 1996, 1997 or 1998, whether a student or lecturer, please get in touch.

"We have spoken to a friend she met there but we are keen to find out if there is anyone else who may still be in touch with her."

He added: "Margaret's carers have said that they believe she has a private side to her life and that she may have friends that they are not aware of.

"We are currently working with very limited information which makes this a challenging investigation.

"If you know or knew Margaret, please get in touch with the investigation team based at Greenock on 101. Any small piece of information may be able to assist us."