Detectives investigating the disappearance of Bradford-born student Shafilea Ahmed six months ago are still making regular visits to the city for clues to her whereabouts.

But after conducting informal interviews at the homes of Shafilea's extended family in Girlington last week, police say they are no nearer to finding her.

Searches of wasteland in Warrington, Cheshire - where Shafilea lived with her family - have been exhausted. Possible sightings have been ruled out and equipment which can be used to detect if earth has been recently disturbed has found nothing.

Agents have been employed to work on behalf of Cheshire Police in Pakistan where the 17-year-old's family come from, but they have turned up nothing.

Shafilea's father Iftikhar Ahmed, 44, and mother Farzana, 41 - who were born in Pakistan but moved to Bradford after they married - were arrested on Dec-ember 18 at home in Warrington. They were released on police bail pending further inquiries.

Det Insp Giles Orton, of Warrington CID, said today: "We are in regular contact with 12 members of Shafilea's extended family in Bradford. Most weeks since the investigation began, we have travelled to the Girlington area to carry out further inquiries, which have so far come to nothing. However, we view Bradford as a very important part of our investigation."

Shafilea's parents - Iftikhar, a taxi driver, and Farzana, a housewife - were the last to see Shafilea alive on September 11 at 11pm.

Det Chief Insp Geraint Jones, of Warrington CID, said: "We are talking to the authorities in Pakistan but unfortunately the bureaucracy over there is holding us back. If I had thought Pakistan held the key I would have flown over there myself by now.

"We are still talking to cousins, second cousins and family friends through interpreters. We believe Shafilea bought a SIM card for a mobile phone on September 9 but it was never activated. The chance she is alive and well has diminished. We believe it likely that she has been killed or has been the victim of crime."

Before she disappeared, Shafilea had recently returned from a trip to Pakistan where she drank bleach after being introduced to a proposed suitor for an arranged marriage.

Her injuries required weekly medical attention to keep her oesophagus open to enable her to eat and drink. Police have contacted hospitals and doctors' surgeries across the country but none reported treating anybody who matches her description.

Anyone with information can call Cheshire CID on 01244 615849.