DETECTIVES are today sifting through vital new leads in the hunt for the killer of Hampshire teenager Hannah Foster.

Murder squad detectives said they were following up several promising new leads after a public appeal on the BBC's Crimewatch UK series last night.

The programme featured a four-minute reconstruction of the 17-year-old's last known movements after a night out with friends in Bevois Valley, Southampton, nearly two weeks ago.

Viewers also heard an emotional interview with Hannah's devastated parents, Hilary and Trevor Foster, who spoke of their struggle to come to terms with what had happened to their eldest daughter.

Detectives hunting Hannah's killer believe the teenager was abducted just yards from her Portswood home, probably by a man with a car.

Police think the teenager may have been sexually assaulted before her body was dumped by the roadside in Allington Lane, West End.

Last night Det Supt Alan Betts, leading the murder hunt, codenamed Operation Springfield, said: "We now believe that the motive was sexual and that she was strangled before being left in Allington Lane.

"We are appealing for anybody who may have any idea where she was assaulted. It is possible she was attacked in a lovers' lane or dark area. Members of the public may have seen something and assumed it was a lovers' tiff."

After the programme, Hampshire police confirmed they had received around 100 calls as a result of the high-profile appeal.

Among information passed to the inquiry team was:

Three independent callers who thought they had seen a girl fitting Hannah's description in a hatchback car on the night she disappeared

Sightings of Hannah's khaki satchel-type bag in the Southsea area before it was recovered by police at a glass recycling centre

A possible sighting of the teenager being followed as she made her way home after saying goodbye to a friend at a bus stop in Portswood Road

Several calls about suspicious activity in Allington Lane, where Hannah's body was found dumped in undergrowth two days after she disappeared

Det Supt Betts said: "Yet again the response from the public has been outstanding, and we hope the calls we have received will provide us with information which will add further momentum to this inquiry."

A team of 30 Hampshire police officers was drafted in to man dedicated Crimewatch phone-lines being run out of Basingstoke police station until midnight last night and again from 8am to 1pm today.

Calls were also being taken at the major incident room in Hulse Road, Southampton, where the murder investigation is based, while a handful of detectives working on the inquiry travelled to London to man phone-lines in the BBC Crimewatch studio.

Yesterday police also released a new family photograph of Hannah as part of the Crimewatch appeal.

In an interview broadcast on last night's show, Hannah's mother Hilary, 46, described how she and her husband were tormented with thoughts about how their daughter may have died.

Reliving the morning she woke up and realised Hannah had not returned from a night out, Mrs Foster, a nurse, said: "I instinctively knew that there was a problem. She never, ever failed to communicate.

"It was a very, very terrifying and frustrating day. It was just one of rising panic. I actually wanted to go and smash down all the doors in the neighbouring houses.

"By the time I went to bed, I was certain that she was dead."

She added: "It's the not knowing what she's been through, and just knowing how frightened she must have been at some stage - and we can't get beyond that."

Mr and Mrs Foster described Hannah as a lovely, happy girl who was fiercely protective of her younger sister Sarah, 14.

The teenager, who hoped to become a doctor, had been studying for A-levels at Barton Peveril College, Eastleigh, and had already secured a place at Bristol University.

Police said she had been out with friends at two pubs in Bevois Valley before she disappeared on Friday, March 14.

After seeing a pal on to a bus, she headed off on the five-minute walk to her family home in Grosvenor Road, but she never made it there.

Detectives believe she was abducted in the street just yards from her home. One witness has described hearing screams and the sound of a car.

Police have confirmed a 999 call was made from the teenager's mobile phone at 11pm that night but there was no conversation between Hannah and the operator.

Her body was discovered in undergrowth near a hump-back bridge in Allington Lane, West End, two days later. A post-mortem revealed she had been strangled.

Detectives initially said there was nothing to suggest Hannah had been subjected to a sexual assault. However, earlier this week investigating officers confirmed the motive for the attack was "probably sexual" following forensic examinations and consultations with behavioural and geographical experts.

Any information to the Operation Springfield incident room on 0845 045 4545, or the anonymous Crimestoppers line on 0800 555 111.