A letter saying sorry and reportedly signed by child killer Roy Whiting has been left at his victim's grave.

Sarah Payne's mother said whoever wrote the note, which had the initials RW, was sick.

Similar notes and flowers have been left on the graves of Soham schoolgirls Holly Wells and Jessica Chapman, purporting to be from killer Ian Huntley.

The Home Office said any suggestion that the flowers and notes had been sent by the jailed killers was "utterly untrue".

Huntley, 31, and Whiting, 46, were reportedly questioned in their cells at Wakefield Prison, West Yorkshire, over the mystery notes.

Sara Payne, 37, threw the card and flowers away.

She said: "Whoever has done this has desecrated our daughters' graves. I can't imagine what kind of sick individual would do such a thing."

It remains unclear whether the message scrawled on a memorial card wrapped around a dozen white roses had been left on murderer Roy Whiting's behalf or as a cruel hoax. But handwriting experts say the notes could have come from the killers.

The flowers were left at Bur Hill Cemetery in Hersham, Surrey, and the note, written in blue biro, read: "To Sarah, Sorry - RW".

Sarah, eight, was snatched and killed on a day out in Sussex six years ago.

Her grandmother, Lesley Payne, said: "I really don't know the full story. All I know is that it's being investigated. Sara is very upset, obviously. She just wants to get to the bottom of it."

Pressure group Phoenix Survivors, of whom Sara is a member, called those responsible "evil, rotten b*****s".

A statement for the group, which acts for the victims of child sexual abuse, said whoever had left the flowers had "crossed a line".

It added: "These innocent families have the right not to be harassed or intimidated by you and you will pay for your unspeakable cruelty."

The messages were left as Whiting mounts an appeal against his 50-year jail sentence.

He admitted for the first time two years ago kidnapping and killing Sarah as she played in cornfields by her grandparents' home in Kingston Gorse, near Littlehampton.

The Home Office would not comment on the possibility that one of Whiting's visitors had left the white roses and note for him.

A Home Office spokesman said: "We categorically refute suggestions there is any connection between Roy Whiting and the flowers.

"As far as we are aware no prison officer has left them on behalf of him.

"Obviously we don't know who did it but we do know who didn't do it and it wasn't him."

Holly Wells and Jessica Chapman, both aged ten, vanished in Soham on August 4, 2002. Their bodies were discovered 13 days later.

Huntley, the local school caretaker, was convicted of their murders in December 2003.