Rival British-born mullahs battle for the loyalties of Mexico's Muslims

The Imam of Mexico City has a knotty problem. How can devout Muslim women go water-skiing in modest attire without getting all tangled up in the towline?

Even head-to-toe coverage in a wetsuit won't do: the fabric would cling revealingly. Baggy sweatsuits would get too soggy if the women fall, and far too steamy if they manage to stay upright under the tropical sun.

But Imam Omar, born Mark Weston in Watford, seems unfazed by the problem of maintaining his own modesty while zipping across the motorboat's wake. He wears a T-shirt and keeps fiddling with his trunks to make sure his knees aren't visible, in keeping with Islamic rules of decorum. Somehow he keeps his full beard, two fists long in true Taliban style, from getting whipped back by the wind into his eyes like some furry blindfold.

For a 29-year-old Koranic scholar in overwhelmingly Roman Catholic Mexico, where most of the estimated 500 Muslim families are relatively recent converts, it requires ingenuity to stick to all the tenets of Islam. It would be a bit easier in Brazil, where there are a million Muslims, or Argentina, where 300,000 regularly attend mosque. But this unconventional imam seems up to the task.

Imam Omar's Christian parents emigrated to Mexico with him before he started primary school. "I was a water-ski bum and a drifter for years," he confides, and even after he and his brother discovered Islam through Yusuf Islam – or Cat Stevens, as he was previously known – in 1989, he has lost none of his zeal for the sport. Rather than build a run-of-the-mill Koranic study centre, he is constructing a lakeside retreat for middle-class Muslims that is far away – in every sense – from the beach distractions of bikinis and tequila slammers.

The resort, near his boyhood summer home in Tequesquitengo, Morales state, is an hour's drive south of the Islamic cultural centre he runs in the capital, and within six weeks he hopes to finish rooms for his first visitors. Workers are still slapping stucco on the pointed archways that overlook the shore.

"Muslims like to relax on vacation, but we have special needs, such as prayer five times a day or separate assembly halls for men and women. The possibilities are exciting. After a ski, have a class of Koran," he said, towelling off in time to pray before sunset.

Finance for the project has quickly fallen into place. Charitable donations for spreading Islam in Mexico arrive regularly from a mosque in Didsbury, Manchester, as well as from a wealthy Saudi Arabian sponsor who prefers to remain anonymous. Hakeem Olajuwon, a professional basketball player with the Houston Rockets, is the most prominent Black Muslim backer. "The minute I finished telling the guy about my plans, he wrote out a cheque straight away," Imam Omar said, still incredulous at such decisiveness. "Praise be to Allah."

Mexico's Islamic world is divided between Imam Omar and another Briton, an elderly Scottish Sufi mystic who once played a bit part in a Fellini film. Followers of Shaykh Abdalqadir al-Murabit, born Ian Neil Dallas, have been active since 1995 among the Maya of the rebellious southern district of San Cristobal de las Casas, where they have set up a madrasa (a religious school), a bakery and a commune. They suggest that Imam Omar has sold out to the Saudis, and is spreading Wahhabism, a reactionary and puritanical brand of Islam.

"The extremists come like a plague of insects to infest a healthy plant," warns Esteben Lopez, who leads Mayan converts in daily Arabic recitation at the madrasa. Their water-skiing rival shrugs them off. "Oh, anyone who points a finger at them is labelled a Wahab," he says. "These Murabitun are kind of militant Muslims. Loony Tunes."

The Murabitun, influenced by Ayatollah Khomeini's revolutionary thought, have been active in Chechnya, South Africa and, now, Chiapas – all troublespots. Their leader, who lives in a village near Inverness, promotes "holy war" against Jewish banking, praises Hitler and writes off the 11 September attacks as a plot to discredit Islam.

Aureliano Perez, a former professor who now calls himself Emir Nafia and pursues donations in Dubai and the US for the San Cristobal commune, dismisses concerns about Shaykh Abdalqadir's beliefs. "Since the attacks in New York, we Muslims have been under a black cloud," he admits. "People think any man who prays to Allah is a possible assassin. But we do not teach such hatred."

For now, the north-south divide is more a squabble than a schism. Emir Nafia acknowledges that a breakaway group of Mayan farmers, some of whom have already made the pilgrimage to Mecca, demand more orthodox worship than that on offer in San Cristobal. Devout songs and Sufi dancing put them off. They have appealed to Imam Omar for instruction and financial support.

"We need religion that is stricter and more correct," insists Juan Gomez, a convert who recently renamed himself Yahya. One wonders what he'll make of the water-skiing.