Police investigating the deaths of Holly Wells and Jessica Chapman were last night granted another 36 hours to question college caretaker Ian Huntley.

Magistrates were still considering whether to grant a similar application to continue the questioning of Huntley's girlfriend, Maxine Carr, 25, who was arrested in the early hours of Saturday.

A police spokesman said: ''Regarding the 28-year-old man, I can tell you that in the last few moments magistrates have approved an application by the police to detain him for a further and final period of 36 hours, expiring at 6.19am on Wednesday morning.

"I can advise you that magistrates are now about to consider a similar application by police with regard to the 25-year-old woman."

Carr was arrested on suspicion of murder and Huntley, 28, on suspicion of murder and abduction.

Earlier, the parents of Holly and Jessica were told that post-mortem examinations on their daughters' bodies had failed to pin-point the cause of death.

The five-hour examinations proved inconclusive and further tests will be needed over the next few weeks. This means the girls' funerals cannot be held for some time.

Holly's parents earlier made a brief visit to the Church of St Andrew in their home town of Soham, Cambridgeshire, where the churchyard has been transformed into a sea of flowers left by well-wishers.

The church has become the focus of an extraordinary display of grief from around the world and from the townspeople themselves, who have been offered counselling.

Books of condolence have been set up at nearby Ely Cathedral and in other churches across the country. A book has also been opened on the Internet.

The website, called Soham Tragedy, can be accessed via the Cambridgeshire Police site at www.cambs.police.uk

Prime Minister Tony Blair, on holiday in France, was among those said to be "very distressed" about the deaths.