Frustrated relatives say they have been left with a host of unanswered questions four years on from a horrific road crash which killed four of their loved ones in South Africa.

They said incomplete inquiries by the South African authorities have left them with an incomplete picture of the sequence of events which led to the tragedy.

Engineer Jeremy Monk, 49, his wife Kathrine Monk, also 49, their daughter Bryony Monk, and her boyfriend Matthew Inman, 22, died when the hire car they were travelling in collided with a truck.

The crash happened at the Saldanha crossing on the road between Cape Town and Vredendal on December 14, 2004.

Mr Monk and nursery teacher Mrs Monk, of Station Road, Mayfield, near Crowborough, Bryony, of Budock Terrace, Falmouth, Cornwall, and sales assistant Matthew, of Church Street, Falmouth, died at the scene.

Today an inquest at Hastings heard student Bryony had been at the wheel of the rented blue Nissan Almera when she emerged from a minor road onto a major road and into the path of the truck.

In evidence given by the truck driver, Geel Reed, to the South African authorities, he stated that he saw the Nissan come to a halt at the stop sign at the T-junction.

After being satisfied she had noticed him, he said he increased his speed again but as he was about 40m from the T-junction he noticed the Nissan move out.

To avoid a collision, Mr Reed - a truck driver since 1986 - said he first thought about passing the Nissan on its left-hand side but after realising he would not be able to he tried to pass it on the right - but then crashed.

The force of the impact led to the Nissan's roof being torn off and the truck came to rest more than 300m away.

Toxicology tests carried out on Bryony gave a negative reading for alcohol but relatives were frustrated at not knowing whether similar tests had been conducted on the truck driver.

Outside court, they said inquiries by the South African authorities left them with more questions than answers.

Gary Huxtable, 28, the husband of the Monks' eldest daughter, Freya, 27, said: "We have so many questions. We don't know whether the driver of the truck had a toxicology report done on him.

"We don't know whether either vehicle was examined. In this country they obviously would have done checks. We don't know whether the brakes were OK or when the last service or MOT were done.

"All of this stuff should have been done but hasn't. We are frustrated and angry.

"We are left in a situation where we will have to decide whether we want to find out whether the South African police authority have done everything they are supposed to have done because by UK standards what they have done is not enough.

"It's a joke almost."

Matthew's mother, Lesley Brunt, from Chesterfield, Derbyshire, said: "The investigation by the South Africans has just been farcical. It wouldn't happen like that here."

No criminal proceedings have been taken against anyone following an inquest in South Africa in October 2005 during which magistrates said they could not find that the truck driver was negligent.

East Sussex coroner Alan Craze recorded verdicts of death from a road traffic crash.