They came in search of paradise

But it was what the makers of The Beach left behind that sparked the biggest drama of all.

It should have been an easy ride: a film adaptation of a gripping international bestseller starring Hollywood heart-throb Leonardo DiCaprio, displaying his sun-kissed torso on an idyllic, palm-fringed tropical island.

Instead, director Danny Boyle's version of Alex Garland's novel The Beach has been a thorn in the side of its luckless production team ever since they first set foot in Thailand, their chosen location, more than a year ago. Now, just three months before the film is due to be released, 20th Century Fox is mired in a legal wrangle over alleged damage to one of Thailand's most beautiful beaches. The case starts in earnest next week; if found guilty, the studio faces a fine of up to pounds 1.6m.

Garland's book tells the dark and sorry tale of a group of backpackers whose search for the perfect, unspoilt beach leads them to a utopian community living in a seeming paradise on a secret island. But things fall apart - in this case, in such spectacularly gory fashion that the climax of Lord of the Flies pales in comparison.

The trouble for Fox began in July of last year, when producer Andrew Macdonald, who made his name along with Boyle on the hits Shallow Grave and Trainspotting, found his own "perfect" beach in Krabi in southern Thailand. He gained permission from the authorities to film on Phi Phi Leh, a tiny, uninhabited island in the sparkling Andaman sea, surrounded by dramatic limestone cliffs and limpid waters.

The problem was, the island's secluded Maya Bay was not quite perfect enough. For a start, it wasn't palm-fringed. Not a coconut tree in sight. There were also a couple of sand-dunes and some unsightly shrubs in the way. As Santa Pestonji, the film's Thai co-ordinator, put it at the time: "We need to dress it up a bit." So Macdonald was given the go-ahead to lend Mother Nature a helping hand, by digging up part of the beach and planting 100 fully grown coconut trees. There was an immediate outcry.

What angered environmentalists was not the shooting of a film on Phi Phi Leh - the Hollywood flop Cutthroat Island was filmed in the same bay without incident. It was that permission was given to alter the landscape of a National Park where officially no flower may be picked or stone overturned. Fox had agreed to pay what seemed a paltry figure of pounds 66,000 for the privilege, plus a deposit of pounds 83,000. Accusations began to fly that Thailand's heritage was "up for grabs".

"A national park should not be touched," said Ing Kanjanavanit, a leading environmental protester, and herself a film-maker. "Most wild beaches have bushes, not coconut trees, but that doesn't conform to Hollywood's idea of a tropical island." She and other environmentalists issued dire warnings of what would happen should the bay's delicate ecosystem be tampered with. "The shrubs hold the sand- dunes together," she said. "If they remove them, the dunes will collapse and wash down into the lagoon, eroding the beach."

What she and others predicted has already happened, at least according to local activists who have seen the beach in the last fortnight. Boonkasem Saekaw, head of the local group Krabi Artists for the Environment, has posted photographs of the beach on the Internet. These, in turn, led the editor of the English-language daily newspaper, The Nation, to describe Maya Bay as "a forlorn scene of ugly bamboo fences and dead native plants - the legacy of a promise that could not be kept".

Boonkasem says that nearly half the original beach area has now disappeared. "The producers tried to restore the beach by holding the dunes in place with bamboo sticks, but it hasn't worked. The waves have washed so much of the sand away that I think the damage is irreversible. The beach has been raped."

The Fox production team was apparently caught unawares by the strength of local feeling against their film. In their eyes, they were simply going to rearrange a beach temporarily and then put it back as it had been, minus the three tons of rubbish they said they had removed. Macdonald sounded hurt and dumbfounded when he wrote in The Nation: "We never expected to be faced with the criticism that we have received over the last few weeks."

The fuss over Maya Bay seemed absurd when there were other more serious environmental travesties to worry about. Just next door, on Phi Phi Don, in the same marine park as Phi Phi Leh, unchecked development has meant that what was once a stunning island is now a mess of beach huts and noisy bars.

As Macdonald himself wrote: "Why doesn't someone write about the environmental damage that's going on in other places in Thailand? We are regulated, that's the whole point. We are spending a lot of money and employing a lot of expertise to make sure it's done with the utmost care and sympathy."

But to the protesters, Phi Phi Don and the like are already lost causes. Instead, they say they wanted to protect one of Thailand's few remaining untouched beaches and were not going to pass up the chance of using one of Hollywood's biggest names to highlight what they saw as a betrayal by their government. When the bulldozer moved onto the beach, protests grew so vociferous that preparations for the film were halted after just two days while a Royal Forestry Department (RFD) committee assessed the environmental impact. Protesters began camping on the beach, erecting signs demanding that the film-makers "stop raping Maya Bay" - but to no avail. A month later, the RFD endorsed the film once more.

When DiCaprio finally arrived in January, he had more than the usual crowd of hysterical teenage fans to deal with. The press bobbed about in boats outside his hotel in Phuket and followed him to Maya Bay in the hope of capturing the small paunch he was rumoured to have acquired. Protesters jostled with them in yet more boats, displaying banners urging Leo not to "break our laws and our hearts".

DiCaprio was photographed doing the Thai wai, a traditional bow of respect, and the film was blessed by Buddhist monks, but still the situation did not improve. Rumours spread: Leonardo had police protection and was so alarmed by the protests that he'd hired a food taster. Macdonald was rumoured to have employed gunmen to protect the set - something he emphatically denied.

The filming went ahead, however, with 40 fewer coconut trees than originally planned; and afterwards, the producers set about restoring the beach, replanting the native plants (which had been kept in a nursery) and reconstructing sand-dunes supported by bamboo sticks and protected by a fence. Finally, cast and crew went home, but not before even the elements turned against them: in April, they were forced to jump from a sinking boat in stormy seas, abandoning their equipment. It must have seemed like the last straw.

Then to cap it all, two weeks ago another huge storm hit Thailand - the biggest in 30 years - causing severe flooding. Ross Palmer, a horticulturist for 20th Century Fox, visited the island on Tuesday and said he was not at all worried by what he saw. "During stormy periods, nothing will stop the sea from taking what it wants, not even plants. It is perfectly normal for the sand to erode during the monsoon, it just sits in the bay and gets pushed up again at the end of the season. The beach will look quite different in February."

Protester Ing Kanjanavanit is not impressed by this argument, however. "The waves in Maya Bay are always awesome because it's an inlet, but I've never seen this degree of erosion," she said. "What they have done is like weakening someone's immune system, so that something that can usually be coped with becomes life-threatening."

For their part, Sarah Clark, the spokeswoman for the production team, says the film-makers are monitoring the beach carefully, sending regular scouts to report back, and flying Mr Palmer out from England when required. Andrew Macdonald is, she says, confident that the court will rule in Fox's favour, as they have looked after the island "from beginning to end". The case, brought by the local government and a local administration against Fox, Santa International Film Production, the forestry department and the agriculture ministry, resumes on 19 Nov. But perhaps the truth will only be revealed by the beach itself next year.