British actors Robert Pattinson and Charlie Hunnam star in the true-to-life jungle adventure story "The Lost City of Z" about the ill-fated search for a vanished South American civilisation.

The movie, given its international premiere at the Berlin film festival Tuesday, was directed by US filmmaker James Gray ("The Immigrant") and is based on a bestseller by David Grann, a New Yorker staff writer.

Hunnam, best known from the "Sons of Anarchy" television series, plays Percy Fawcett, a British mapmaker and explorer who believed there was an advanced society in the Amazon long before the arrival of the Europeans.

Pattinson, the heartthrob from the "Twilight" franchise, is his aide-de-camp Henry Costin, who joined him on several treacherous expeditions before and after World War I looking for what Fawcett called "The Lost City of Z".

Sienna Miller ("Foxcatcher") appears as his wife Nina, an independent woman with a taste for adventure who longed to accompany Fawcett on his travels but stayed back in England to raise their three children.

The story plays up both the lengths to which Fawcett would go for recognition in Britain's rigid class system, as well as his progressive streak, with a desire to disprove Western notions of cultural superiority.

- 'Racist, colonialist view' -

Gray said those ideals appealed to him given the "wave of nationalism that's gripping the world" today. 

"The whole world, the human race, has this terrible urge, need, desire, tendency to rank, to put people into categories," the director told reporters in Berlin.

"The movie unfortunately is, I think, as relevant as ever because we cannot close the book on what is clearly a -- let's be honest here -- white and very racist, colonialist view of the world."

Gray said his team spent weeks working with four native tribes in the Amazon but he resisted the urge to make an "anthropological movie" focused on exotic differences.   

"I was terrified of course of being condescending," he said. "I think we need to be reminded that we're all made of the same clay."

The film features encounters with native peoples during the treks, which were shot in Colombia, set against vivid World War I battlefield scenes from the Belgian trenches.

"I thought it was essential story-wise because it would really give full colour to the lie that is the idea of the advanced European civilisation," he said. 

Faced with growing scepticism at home and a chronic lack of financing, Fawcett, a gifted storyteller, managed to capture the imagination of newspaper editors around the world, sending them breathless dispatches in exchange for cash.

The articles made him a global star in his lifetime, and heightened the tragedy around the mystery of his eventual disappearance in the Amazon in 1925 alongside his son Jack.

- 'Pretty adventurous' -

Hunnam said the work on set had been hairy at times, with scorpions, snakes and poisonous spiders often coming too close for comfort.

"It was pretty adventurous, he said. "There were all manner of things on any given day that thought it might be a nice idea to bite and attempt to kill us."

Pattinson, who has branched out to more adult fare in recent years, appearing in David Cronenberg's "Maps to the Stars" and "Cosmopolis", said it was fun getting out of his comfort zone. 

"You don't get that many opportunities in everyday life to just disappear into the jungle," he said.

"When I first read the script, I loved there being areas of the world that you could still explore and were totally uncontrolled." 

He said today's hyper-connected world "takes away that mystery and kind of majesty of going into the unknown". 

But he admitted: "I tell myself I would kind of prefer that. But really I would probably want to have my Twitter."

Source: AFP