The killer of Huddersfield backpacker Peter Falconio in Australia's Outback has launched a new appeal to overturn his conviction.

The Northern Territory Criminal Court of Appeal has confirmed that it received the application from Bradley John Murdoch for leave to appeal today.

It has been lodged outside the normal time allowed for appeals.

It is believed Murdoch is basing his appeal on an assertion of misconduct by the Crown prosecutor at his original trial.

"This is an allegation that the crown prosecutor at the original trial, Rex Wild QC, improperly groomed the star crown witness Joanne Lees in how to give her evidence,'' Murdoch's barrister Peter Faris QC said in a statement.

"This allegation brings into question the entirety of Lees' evidence.'' 

Murdoch, 55, was convicted and sentenced to life in prison in 2005 for Mr Falconio's murder.

He was also been found guilty of the assault and deprivation of liberty of Mr Falconio's girlfriend Joanne Lees.

Joanne Lees and Peter Falconio in Australia
 

The body of Mr Falconio, from Hepworth, has never been found.

Murdoch has been serving his sentence, with a minimum non-parole period of 28 years, at the Alice Springs Correctional Centre.

Mr Falconio is believed to have been killed near Barrow Creek in July 2001, when he was 28.

He had been travelling with Ms Lees, from Almondbury, in a Kombi van on the Stuart Highway near Alice Springs, about 1,600 kilometres south of Darwin.

Murdoch's 2005 trial was told that he had stopped the van at night and killed Mr Falconio, later disposing of his body.

Ms Lees escaped by eluding him in scrubland and later running on to the road where she was seen and rescued by a truck driver.

Murdoch has always maintained his innocence.

His conviction was largely based on DNA evidence and the testimony of Ms Lees.

No date has been set for an appeal hearing.

A previous application by Murdoch for leave to appeal was dismissed by the Northern Territory Criminal Court of Appeal in 2007.