Horrific internal injuries inflicted by lap seat belts in a crash mean it would be better not to wear one at all, says a coroner - a claim rejected by Land Transport New Zealand.

Huntly coroner Bob McDermott, whose area includes several major accident blackspots, said lap seat belts, commonly fitted to the middle of the back seat of a car, should be banned due to the "horrendous injuries" they caused to crash victims.

"There is no polite way to put this - they are almost cut in half ...

"Do they wear nothing and end up through the windscreen, or suffer major damage to their internal organs from the force of the lap belt on impact?" said Mr McDermott.

"It would be better not to wear lap belts ... or regulations should be made making it compulsory for such belts to have a diagonal belt as well."

Land Transport spokesman Andy Knackstedt agreed a three-point belt was better but said that wearing a lap seat belt still made the passenger safer.

"If the only thing available is a lap belt, it's certainly better than not wearing a belt at all, particularly in a high-speed crash, where the person would probably end up going through the windscreen and ending up on the road."

Mr McDermott cited the case of Hamilton woman Ana Marie Le Roux as particularly troubling.

Mrs Le Roux is still suffering from major internal organ damage as a result of a head-on crash in January 2003 on State Highway 1 north of Huntly.

"We and everyone I know completely avoid sitting in a car if we don't have a three point-belt," she told the Herald last night.

Mrs Le Roux spent 11 weeks in Middlemore Hospital with internal injuries and a broken back, then a further two weeks at the Otara Spinal Unit. She still takes medication for her injuries.

Her experience has led her to use a harness for added protection if she ever has to use a lap belt.

"The thought of a lap belt on anyone absolutely freaks me out. I'll never sit in a lap belt again."

Mr McDermott was also appalled at the death of 77-year-old grandmother Annie Borgman, killed in a crash on State Highway 1 near Wellsford on January 15.

Seated in the vulnerable centre seat, the impact of the crash snapped Mrs Borgman's body around the lap belt she was wearing and ruptured her internal organs.

Gary Abbott, of the North Shore serious crash unit, said that Mr McDermott made a valid point but that people should buckle up.

"It's safer than not wearing a lap belt, but the lap belt is not a good type of belt to have in a vehicle."

Lap belts are legal in new and old vehicles in New Zealand as well as overseas. Land Transport said it had to accept the approved vehicle standards of Australia, Europe, Japan and the United States, as New Zealand did not have a domestic car manufacturing industry.

These vehicle standards generally require three-point lap and diagonal belts in the front seats and outer rear seats but still permit lap-only belts in middle rear seats.

Land Transport said a lap belt could be replaced by a lap-and-diagonal seat belt provided it met an approved safety standard.