The father of a British student who disappeared for three weeks in a South American jungle spoke of his relief today after being reunited with his son.

Michael Dance said he never gave up hope that Luke, 19, was alive after he vanished in a remote corner of Bolivia.

He said the money he spent tracing his son was "well worth it" after seeing Luke for the first time yesterday when he arrived at Heathrow Airport.

He said Luke's appearance had changed dramatically following his ordeal and described him as "frail" after losing three stone in weight.

Mr Dance, 48, from Climping, near Littlehampton, said: "Luke looked like he had lost a lot of weight, probably about three stone.

"He was very frail. Fortunately I don't suffer shock easily, but it was very good to see him and he seemed in good spirits. I have spent a lot of money trying to find him but it was worth it."

Luke, 19, from Worth, near Crawley, had originally been on an expedition with fellow members of the East Midlands Universities Officer Training Corps, apparently to map Inca trails for the Peruvian government.

But six weeks into their travels at the end of August they decided to split up and he embarked on a two-week solo trek.

The idea was to meet up again on September 15 in Lima, Peru, for the flight home but Mr Dance said he was frantic when his son didn't turn up.

Mr Dance, a retail manager, said: "He never made it. I went to Heathrow airport on the 16th expecting him to be coming back.

"He wasn't there and I was ringing round frantically trying to find out what had happened to him.

"In the end I managed to get to speak to one of his friends at 2am and he said that Luke had been making his own way back and didn't know where he was."

Mr Dance said Luke had fallen down a waterfall during his journey through the sub-tropical jungle in the Yonga region of Bolivia.

He said: "Apparently he almost drowned. His backpack saved his life really because it kept him buoyant in what was nothing but a whirlpool. The problem was there was another waterfall a bit further along that he couldn't negotiate.

"He eventually found a ledge and created a kind of shelter. He stayed there for two weeks, surviving on his rations in his backpack, waiting to be rescued but no one ever came.

"When his rations finally ran out he realised he would have to make his own way back, so he jumped down the second waterfall. It must have been a brave thing to do.

"He then walked to the nearest village and stayed overnight before heading back to La Paz by bus.

"I never thought he was dead at any point. He wanted to go to Sandhurst after getting his degree and he has a substantial amount of survival and military training.

"I think that, and the fact that he is a strong character, is what made the difference."