Pinned to a wall in the cluttered, ramshackle office at Tito's Beach Bar, overlooking the Mediterranean sea at Mojacar, south-east Spain, are the photographs of three men. One of them is holding up an Oscar statuette. The moustache, receding hairline, arched eyebrows - so perfect they seem plucked - and the almond-shaped eyes belong to the familiar face of that American icon and global brand-name, Walt Disney.

The same features are repeated on an unfamiliar face below. The moustache is bushier and the face is fleshier, but the resemblance is strong - although the stiff, gentleman's pose and formal clothes date the subject to the early part of last century. The third photograph is of a thin-lipped, long-nosed man with his hair slicked-back in a side parting. Behind his smile lies a hard, narrow, timeworn face.

When Tito del Amo, the American one-time hippie who owns the bar, invites visitors to guess which of the latter two is Disney's father, they normally plump for the first. They are wrong - or that, at least, is what the official history books of Hollywood say. Elias Disney, the Christian fundamentalist who beat his son regularly and drove him to seek refuge in a rich imagination, is the thin, mean-faced man. The other is Gines Carrillo, a doctor whose family were the "señoritos", the ruling clan, of Mojacar until the middle of this century. That should be the end of it. But it is not. Because Del Amo, like most of Mojacar's 5,000 people, is convinced that old Dr Carrillo was the true father of Walt Disney.

They are not alone. Disney's family may not like it, but two American authors, the showbusiness biographer Marc Eliot and Disney specialist Christopher Jones - son of one of Walt's press agents - are separately trying to prove that he was theillegitimate son of Dr Carrillo and a local washerwoman, Isabel Zamora. She, it is said, took him to the US but abandoned him when he was a few months old.

The story is irresistibly, perhaps impossibly, romantic. Mojacar is a fairy-tale place - a whitewashed village perched on a towering slab of rock, its houses clinging to the edge of the slopes, looking out over a sparkling, emerald sea. Where better for a creative genius - obsessed by castles, magic and small, vulnerable animals - to be born? The Mojacar tale combines forbidden love, an orphan child, wicked step-parents and even the sinister presence of J Edgar Hoover and his G-men. "This is a story of an orphan, brought up by nasty parents, who becomes a wizard," says Jones. "It is the story of Harry Potter gone sour." And, Jones says, the only time Walt was challenged - by a well-known Disney animator - on whether he might have been born in Spain, he added further fuel to the story. "Who knows?" he replied.

America's great economic and cultural icon - the tale goes - was the product of an illicit tryst that broke both class frontiers and Catholic strictures. His mother was hurriedly married off to a local miner, Jose Guirao, who had no option but to follow the bullying Carrillo family's instructions. Mother and child quickly emigrated to the US - where they moved into her brother's Chicago house in State Street, not far from the Disneys' home on Tripp Avenue. The supposed brother, Juan D Zamora, is listed in the 1901 Chicago phone book as a circus acrobat. When Isabel could not, or would not, look after him, baby Jose was secretly adopted, presumably as an act of charity, by Elias and his wife Flora Call - who lied to the local priest, and, possibly, to Walt.

"I rejected the idea outright when I first came here in the 1960s. We were too busy having a good time," says the gently-spoken Del Amo. Back then, Mojacar was an almost Mediterranean paradise where a small group of hippies could get safely psychedelic - and where their children could scamper up and down the irregular flagstones of the village's narrow, steep streets. Del Amo admits that he now sees Disney's face in the Carrillo family and all over the village. "The man from the electricity company came and I thought, well, he also looks like Walt," he says.

Del Amo is from a wealthy Los Angeles family. As a small boy, in the 1940s, he lived on Carolwood Drive, in the classy suburb of Holmby Hills, right across the street from the Disneys. "From my house I could see a model train in his back yard with cars big enough to sit on," he says. He even visited the first Disneyland with Walt while it was still being built. Del Amo's obsession is shared by Jones. He first heard the Mojacar tale as a boy from his father Tom, Disney's favourite press agent. Not that Tom would have liked his attempts to prove it. "My father liked him very much. He was a very loyal soldier," he says.

Like Del Amo, Jones has a photograph of himself as a boy with "Uncle Walt", taken watching a Disneyland parade in the mid-60s. "He was a very impressive kind of a guy. At that age, you didn't forget who Uncle Walt was," he says. "My own memories of Walt Disney are as good as any you could have." Now Jones, his wife and their cat have moved from Italy to a hill town an hour's drive from Mojacar as he works on a book, provisionally entitled Behind the Mask of Uncle Walt, which aims to prove the illegitimate son theory.

These efforts to clarify Walt's parentage are not appreciated at the Disney empire's headquarters in Burbank, California. America's 49th biggest corporation does not like the origins of its brand name questioned - nor does the company or family, understandably, want the word "bastard" attached to it.

In real life Uncle Walt was a devious, megalomaniac, racist, egocentric genius. Jones says he once sacked an Indian employee because he was so dark he looked like a "nigger". His hatred of Jews, especially those from New York, was legendary. All of this, however, was pretty standard for the place and the times. His was the Hollywood of the House Un-American Activities Committee - with which he collaborated enthusiastically, following Ronald Reagan on to the stand - and violent studio strikes. He tried to use the mob muscle of hoodlum Willie Bioff to bust these. Walt was also vice-president of the rabidly rightwing Motion Picture Alliance for the Preservation of American Ideals. Eliot says he was a freelance agent for J Edgar Hoover, with a 600-page thick personal file at FBI headquarters.

But 29 Oscars do not lie: even his fiercest critics would not dispute that the Disney company is the greatest film cartoon factory of all time. And the mythical, marketable Walt is a friend to every child on the planet - the man who understands the inner workings of their minds, whose films reach out to their instinctive need for security, love and parental protection. The father of Bambi, Dumbo, Snow White, Donald Duck and Mickey Mouse is sacrosanct, especially this week - when the 100th anniversary of his birth is being celebrated. "He is everybody's favourite uncle," says Jones.

That vision of Disney is still being peddled. In its in-house centenary biography, broadcast on the company's own ABC channel in the US and produced by grandson Walter Elias Disney Miller, Walt's only recognised vice is smoking. Reviewing it in the New York Times, Julia Salomon wrote: "In the Disney universe, cleanliness of character, and cleverness - American virtues - prevailed every time over more sinister forces."

When Eliot floated the Mojacar connection in his 1993 biography, Walt Disney: Hollywood's Dark Prince, using FBI papers signed by Hoover to cast doubts on Walt's origins, the family hired William Webster, FBI director under George Bush Sr, to refute that and other claims about his role as a prized FBI informer.

The family calls the Mojacar connection a modern myth and, in its way, flattering. "It is nice that the Hispanic community would like to adopt Walt," says Katherine Greene, who, with her husband Richard, is the keeper of the Disney family's museum and their occasional spokeswoman. "It seems outlandish to the family. They know the truth."

Family snapshots of Walt with Elias's other children, the Greenes say, prove the opposite to Del Amo's pictures. "Sometimes he looks so similar that it is hard to tell which one is him," says Richard, who helped write the recent documentary and is publishing a new, authorised biography, Inside the Dream. So why does the Mojacar story, first aired in Spain's Primer Plano movie magazine in 1940, refuse to go away?

The answer lies not in Mojacar, but in Chicago. For there is no record there of the birth of the city's most famous son. Walt Disney did not officially exist until June 8 1902, the year after his supposed birthday, when he was baptised Walter Elias Disney at a Chicago church. The Disneys told the pastor he had been born on December 5 1901. But it was not until 17 years later, when Walt needed a passport, that Flora would sign an affidavit saying he had been born at their home at 1249 Tripp Avenue, Chicago. Oddly, she signed a second affidavit - presumably on Walt's urging - in Oregon in 1934, a couple of years before her death by gas poisoning.

This undoubtedly troubled Walt. He first stumbled across his own mystery when he tried to join the Red Cross as a first world war volunteer in 1917 - and was initially turned down because he could not prove his age. The fact that it concerned him seems to have been confirmed by Hoover himself. In a declassified FBI document, Hoover pledged to help Disney. "I am indeed pleased that we can be of service to you in affording you a means of absolute identity through your lifetime," he wrote.

Exactly how the manipulative Hoover went about this is not clear. Even 25 years after his death, in 1992, the G-men felt that nearly half the documents on his file still needed to be kept secret. The 600 pages made available to Marc Eliot already showed how the FBI had approved his recruitment as a freelance, unpaid spy, or a "Special Agent in Charge contact". If that could be said in 1992, what on earth was in the FBI files that could still threaten state security? Or perhaps one should ask a different question. Just how far would the US government go to protect the Disney name?

The Greenes say this was just another example of the FBI bureaucracy in action. They have seen the whole file and, though they admit bits are still blacked out, they found no record there of Mojacar. Former FBI chief Webster said Hoover's offer of an "absolute identity" referred to the fact that he had Walt's fingerprints on file. Eliot's book provoked a rare public riposte from Disney's daughter, Diane Disney Miller. "He bases everything [his theory about an FBI connection] on the illegitimate Spanish birth theory, that's why it's all so crazy," she told the LA Times. "Evidently there's a little town in Spain that's supposed to be very pretty; a friend of ours showed us a brochure from there that says 'and among other things, we are also the birthplace of Walt Disney, although he does not choose to acknowledge it'. Apparently the story's been out there for a long time."

The people of Mojacar - and, especially, their American allies - have their own theory about how Hoover went about proving, and then keeping secret, Walt's origins. In 1940, a year after Spain's civil war had ended, a pair of mules climbed the steep track to the village bearing the suitcases of two smartly suited Americans. They found a village that was, literally, falling apart. Its population had dropped from 6,000 in 1900 to less than 1,000 after nearby copper and iron mines closed - and most families had travelled north to seek a better life in industrial Barcelona. Mojacar had no electricity, no phones and no running water. Women carried water back from the public fountain in pitchers on their heads. They gripped their long yellow, white or black headscarves in their teeth when their hands were busy, thus protecting themselves from accusations of " sin verguenza ", or shamelessness. The custom, since disappeared, was a clear indication of the village's Moorish origins.

The Americans asked the way to the church of Santa Maria. There they were met by Father Federico Acosta, a young priest who visited the parish from the nearby town of Turre. His nephew Jose Acosta, arrived from Madrid - where Snow White had just had its Spanish premiere - to spend the summer holidays with him that year. Now a sprightly 71-year-old, this former journalist and trained lawyer remembers his uncle's description of what happened next. "He told us that some gentlemen from the US had come to find the birth certificate of one Jose Guirao. They were shown the page in the register. Later, when he looked again, the page had been ripped out," he recalls.

"He told me they had come not to find Jose Guirao's birth certificate, but to destroy it," says Acosta. Were these Hoover's G-men? Had they been sent to find an embarrassing truth that they could use as a lever over Disney, one of the most powerful men in Hollywood? That is certainly what Jones thinks. That doubt, he claims, gave Hoover a hold over Disney for the rest of his life.

Acosta's second-hand account is corroborated by Jacinto Alarcon, who saw the Americans arrive and later became mayor. Jacinto is dead, but Jones has a taped interview with him in which he tells the story, agreeing on the basic facts with Acosta. "Virtually everybody is convinced he was born here. Only the Americans don't want to admit it," explains Jacinto's son Juan, who now owns Mojacar's tobacconists.

In Mojacar people still remembered little Jose Guirao. Gossip never dies, especially in the narrow streets and even narrower morality of an earlier 20th- century Spanish village. The boy was a bastard, the child of Isabel Zamora and, officially, of a poor miner called Guirao. He had been born in a tumbledown house in the Espiritu Santo neighbourhood.

But Guirao's claim on the child was sketchy. The town's " malas lenguas ", or "poisoned tongues", pointed to the imposing Torreon, the modernist, Moorish home built for himself by the eccentric Gines Carrillo. Behind its wooden doors, carved with floral patterns, some of the village's more exotic events took place.

Carrillo was not just the town's doctor - one of the few people who could see the village's young girls in private - he was also its artistic soul. He built a Venetian-style theatre here and directed plays, holding rehearsals at the Torreon. Children went there to learn instruments, and also to gape at his amazing collection of exotic birds.

Today the Torreon is a small guest house, the stone balustrades of its balconies dripping with deep pink bougainvillaea and girandilla flowers and providing a view of the seashore, two miles away, where Gines Carrillo built Mojacar's first ever beach house, El Duende (literally "the spirit of inspiration").

That house, bulldozed along with the theatre by his children, was a fantasy creation of his own, topped with towers. Its eccentric aspect adds extra weight, in villagers' minds, to the idea that this man must have spawned Walt Disney.

Charo Lopez, the current owner of the Torreon, keeps a framed picture of the old man outside the bathroom. "Disney certainly wasn't born in this house. But this is where he was conceived," she states. "This is like the existence of God. Either you believe he was born in Mojacar, or you don't."

Whatever the truth of the birth it can not be proven. For Mojacar's birth register for 1901 has also disappeared. But nobody doubts that Jose Guirao and Isabel Zamora existed. Everybody, or at least everybody's deceased parents or grandparents, remembered them leaving. But, as with Walt's Chicago birth certificate, nobody can prove it.

Gines Carrillo's legitimate son Diego, another doctor, lives on the beach front. Walt Disney's alleged half-brother, aged 79, shooed me away when I knocked on his door, gesticulating wildly. "I have said all I want to. I've had enough," he said through a mouth filled with strange metallic dental appliances.

A few days earlier, however, he had denied the story in Madrid's El Mundo newspaper. "This stuff about me being Walt Disney's brother is fiction," he said. "The journalist from Primer Plano had obviously heard something about Walt Disney and Mojacar, that's why they came here in 1940. My father liked a good joke, so he said 'yes' to everything they asked."

But even Diego could not resist adding a twist of his own to the story this week. "If you think my father and Walt Disney look alike, you should see pictures of my uncle. He looks even more like Disney - and he did like the ladies," he said. Diego Carrillo's nephew, yet another doctor, confirmed the family line. "Mojacar was a boring place then. My grandfather died when I was young but he was a lecher, a ' viejo verde ', in his old age and interested in the occult. The whole thing was cooked up by Jacinto and him when those journalists arrived from the film magazine."

If it was a joke, Primer Plano not only fell for it but introduced a new element, in the form of a letter allegedly sent to the village in 1925. "Some time ago the parish priest of Mojacar received from the US a letter. It asked for the birth certificate of Jose Guirao Zamora, baptised in 1901, and this letter, which disappeared in the revolution, was signed by Walt Disney. A few days after being sent the documentation for Jose Guirao, Walt Disney contracted marriage with Lillian Bounds. And the life of the gifted artist, creator of a new cinematic theory, took its course many miles from Mojacar, the Moorish pueblo." Lillian was a $15 a week sketcher, who worked for Disney and was married to him for 41 years. A year after he died, she remarried - a fact absent from her own glowing obituaries when she died four years ago. Ironically, or rather spookily, according to Tito, she married a Del Amo family friend and was thence forward known to him as "Aunt Lillian".

If the 1925 letter was an invention, the Primer Plano piece would not have been the first to elaborate on the bare factual bones of this story. Virtually everybody who has written about it has provided a new twist to the tale. Even now, in Cristobal's supermarket, down a narrow alley around the corner from El Torreon, village gossips continue to add new flourishes.

At least three other visits, including one confirmed sighting of a group of American Franciscans in the 1950s, are said to have taken place by Californians seeking Jose Guirao's birth certificate. One well-versed, but definitely false, theory even places Isabel as a Disney family servant having an affair on the side with the fundamentalist Elias. Another has either her or the child whisked off to the US by a ship's captain.

The Disney family has blamed Mojacar for using the Isabel Zamora story to attract tourists. Mayor Jacinto Alarcon, a wise old bird who transformed the village by giving away empty houses and persuading General Franco to build a state-run hotel on the beach, was certainly capable of that. He even went on TV to tell the whole of Spain about Walt and Mojacar.

A nother, later mayor once took El Amo to a rundown house in town that he had obviously picked at random. "This is where Walt Disney was born," he stated. "But nobody knows that," replied El Amo. "They do now," said the mayor, though he later dropped the idea. Even now the village's tourism councillor, Jose Luis Cano, is not sure what to do with the Walt Disney story. "I want people to talk about Mojacar," he says. "Do you know a sculptor - not a very expensive one - who might do a bust that we can put up?"

In fact Mojacar, now half populated by foreigners and full of souvenir shops, piercing parlours, jazz bars and yoga courses, has been surprisingly unsophisticated about using Walt Disney to its advantage. Many older people prefer not to talk about it. But Father Federico Acosta was no liar. And, in 1940, nobody in this Spanish backwater had even heard of Walt Disney.

Does that mean Jose Guirao became Walt Disney? Only science could sort out the mystery. A DNA test of Disney's offspring, matched to one of the Carrillo family, would be enough to confirm, or discard, the alleged blood relationship. Diego Carrillo and his nephew both say they are prepared to take part in such a test - if only to rid Mojacar, and the world, of any doubt. The Greenes doubt, however, that the Disneys are ready to do the same.

Meanwhile, Eliot has tracked down a man called Manuel Mayorga in San Antonio, Texas, who claims to be the grandson of Isabel Zamora - and to have grown up with the family legend that she was Walt Disney's real mother. "I hope to go and see him soon," he says.

Jones is excited. "This could be the smoking gun," he says. Tito, meanwhile, thinks she may have returned to Spain and married a Valencian called Montbau - whose relatives he is seeking.