Australian police investigating the suspected murder of British backpacker Peter Falconio have suffered a new setback.

They say DNA samples taken from a 29-year-old drifter arrested in connection with another killing do not match those of Mr Falconio's likely attacker.

It was hoped a spot of blood on the clothing of Mr Falconio's girlfriend, Joanne Lees, would link the suspect to his disappearance and help end one of Australia's biggest ever manhunts.

The 28-year-old is thought to have been shot after he and Ms Lees were ambushed on a remote desert road in Australia's Northern Territory on 14 July last year.

Mr Falconio's body has never been found, despite a massive police hunt involving Aboriginal trackers and officers using motorbikes and helicopters.

'Taking it easy'

Police in New South Wales sent the DNA samples to officers in the Northern Territory after arresting the man in connection with a stabbing death in Sydney.

Joanne Lees was tied up and thrown into a van

Northern Territory Assistant Commissioner of Crime John Daulby said his profile does not match that of the man they are looking for.

Officers have been criticised after failing to make a single arrest since Mr Falconio went missing.

In a television interview in March this year Ms Lees accused Australian police of "taking it easy" over her boyfriend's suspected murder.

Gunshot

The 28-year-old vanished after he and Ms Lees were stopped by a gunman on the deserted Stuart Highway north of Alice Springs.

Ms Lees, from Almondbury, near Huddersfield, West Yorkshire, told police the attacker tied her up and threw her in the back of his van, but she managed to struggle free and escape into the bush.

She hid for six hours while he searched for her with his dog.

Ms Lees said she heard a gunshot and police believe it is likely Mr Falconio, from Hepworth, near Huddersfield, was shot and his body dumped.

There is a �97,000 reward for information leading to the conviction of the attacker.