Mrs Hammond's remains have not been recovered

But they have also praised campaigners after a protest outside Darley Oaks Farm in Newchurch, Staffs, was called off on Wednesday.

The farm breeds guinea pigs for medical research and pickets have been mounted outside over the last five years.

The remains of 82-year-old Gladys Hammond were taken earlier this month.

'Emotional time'

They were removed from St Peter's Church in Yoxall and have still not been recovered.

Ch Insp Peter Taylor, from Staffordshire Police, said: "We are once again urging animal rights protesters not to travel to Newchurch this weekend.

"The force is making this plea during what continues to be a difficult and emotional time for the whole family and residents in Newchurch, Yoxall and surrounding areas.

"The force would also like to thank protesters for not attending the protest on Wednesday 20 October and ask that they respect the request not to attend this weekend."

Darley Oaks Farm is run by Mrs Hammond's son-in-law Christopher Hall and his brother John.

Earlier this week, police said the Hall family had received several threatening letters from a writer who claimed to have Mrs Hammond's remains.

A service was held last Saturday to rededicate Mrs Hammond's grave at the churchyard.