Shafilea may have been the victim of an "honour killing", police say

Detectives have also been given 12 more hours to question five of her relatives who were arrested in the city on Monday on suspicion of lying to police.

Shafilea, 17, of Warrington, went missing in September 2003 and her body was found in Cumbria in February.

Police believe she may have been the victim of a so-called "honour killing" after she refused an arranged marriage.

The search in the West Yorkshire city includes at least one house, the BBC has learned.

Shafilea's parents have denied any wrongdoing

A Cheshire Police spokesman said on Tuesday: "I can confirm we are conducting a number of searches at properties in the Bradford area."

Shafilea, who was described as a "Westernised" teenager, had drunk bleach in an apparent protest at the proposed marriage while on a family holiday in Pakistan.

Cheshire Police said they had not ruled out the possibility that she was killed to protect her family's social reputation after refusing a marriage.

Her parents, Iftikhar and Farzana Ahmed, were arrested on suspicion of kidnap but not charged and have always denied any involvement in her death.

They are not among the relatives arrested on Tuesday.

Cause of death unknown

Detective Chief Inspector Geraint Jones, who is leading the Cheshire Police murder investigation, said he had not ruled the couple out of his inquiries.

Shafilea's body was found in the River Kent, near Sedgewick, Cumbria, in February and was identified by DNA tests and jewellery belonging to her which was found at the scene.

A post-mortem examination failed to provide conclusive evidence of how she died.