An investigation into the 1990s disappearance of a student teacher, Deirdre Jacob, who was studying at St Mary's University, Twickenham, has been reopened.

Deirdre had just completed one year of study at the institution when she disappeared after returning to her home in Newbridge, County Kildare, Ireland, in the summer of 1998.

The case was upgraded to a murder inquiry three years ago after the police received more information about the 18-year-old's disappearance.

Detectives investigating the case have been searching a new area near her home following reports of 'unusual activity' in woodland the evening she went missing in July 1998.

Deirdre was one of at least six women who disappeared in the area during the 1990s.

A fresh search of an isolated part of Co Kildare is under way as part of the investigation into the murders of Deirdre and a second woman, JoJo Dollard.

Inspector John Fitzgerald, who is leading the search operation, said a review of the evidence identified the woodland as 'an area of interest', which may be relevant to the inquiry.

Investigators are searching almost three acres of land, which is expected to take up to three weeks.

Mr Fitzgerald said up to 15 people will be involved in the search each day, made up of members of the Garda technical bureau team as well as a forensic archaeologist.

Mr Fitzgerald said the information about the unusual activity was reported some time ago, but, following a review of the murder investigation, it was deemed more relevant than initially thought.

He said: "There was unusual activity noticed in the woodland in and around the time Deirdre went missing, and based on that we felt it prudent to commence a further search of the area.

"The area has been under review for some time. We have carried out a cursory search some time ago and then the recommendation was to commence a search in October as it is the best chance of success based on the fact that it's thick land."

He said Deirdre's family are aware the searches are taking place.

He also said that, while the investigation into the disappearance of Ms Dollard is separate, the team "are mindful" that the location where she was last seen is nearby.

He also said it is important to "manage expectations" and "not get ahead of ourselves".

"Any development is significant but it is a big step for us to take this ground and search it. If evidence is found, it will be assessed and the senior investigating officer will decide where to go from there," Mr Fitzgerald added.

"We would like to thank the public for their assistance and it will take some time to get through and we appreciate their assistance.

"We have a lot of significant assistance from the public and we will see how we go."