The serial sex killer who murdered schoolgirl Vicky Hamilton will not go ahead with a bid to overturn his conviction, his defence team said today.

Peter Tobin, 62, was jailed for life and ordered to spend at least 30 years behind bars after being found guilty of abducting, drugging, sexually assaulting and killing the teenager more than 17 years ago.

In December he lodged a notice of intention to appeal against his conviction.

But the deadline for lodging grounds for appeal has now passed and the challenge will not proceed.

Tobin will still appeal against the length of his sentence, which was one of the stiffest ever imposed by a Scottish court.

A spokesman for Tobin's defence team said today: "Grounds have been lodged in respect of the appeal against sentence but no grounds have been lodged in respect of the appeal against conviction.

"At the present time no grounds have been lodged, so the time limit for that part has expired and it will no longer proceed any further at this stage.

"But it does not preclude an appeal at a future date if other information comes to light."

Tobin was branded "unfit to live in a decent society" by Judge Lord Emslie following his conviction at the High Court in Dundee in December.

He is already serving a life sentence for raping and murdering Polish student Angelika Kluk and hiding her body in a Glasgow church in 2006.

Vicky Hamilton disappeared in Bathgate, West Lothian, on the evening of February 10 1991.

The schoolgirl was waiting for a bus in the town centre to take her home to her mother in Redding, near Falkirk, after visiting her sister Sharon in Livingston, West Lothian.

Her remains were dug up from a shallow grave in a garden in Margate, Kent, last year.

Tobin was unanimously found guilty of Vicky's murder after the month-long trial in Dundee.

During the trial, prosecutor Frank Mulholland QC, Scotland's solicitor-general, described the murder as "a barbaric act" and an "atrocity".

The trial heard Vicky's purse was found near Edinburgh's main bus and railway stations 11 days after she vanished, leading police to investigate whether she had run away from home.

DNA matching the profile of Tobin's son, who was three years old when the schoolgirl vanished, was later found on the purse.

The jury of 12 women and three men also heard a knife with a piece of Vicky's skin on it was found in the loft of Tobin's former home in Bathgate.