PATMOS, Greece (AP) _ Nightclubs and nudity are banned on this island where tradition holds that St. John wrote the New Testament's Book of Revelation in a cave overlooking the Aegean Sea.

Under a special government decree, Patmos has a unique status among Greece's 200 or so inhabited islands as a ''holy island'' still dominated by its 900-year-old Byzantine monastery.

''We prefer our visitors to be pilgrims rather than ordinary tourists and we would like them to respect our tradition,'' Abbot Isidoros, who heads the 30-member community at the Monastery of St. John the Theologian, said in an interview.

But plans for an airport coupled with widespread publicity for the monastery's 900th anniversary celebrations are expected to bring mass tourism to Patmos in the coming years.

The tranquillity of Patmos, a rocky outcrop in the Dodecanese group of islands with around 2,000 residents, attracts wealthy Greeks and foreigners who have restored scores of traditional mansions clustered beneath the monastery's gray fortress-like walls.

Many have given donations to the monastery, to help maintain its library of rare manuscripts and early books, along with a collection of priceless icons - portraits of saints painted in gold and bright colors.

''Patmos is still a place apart, with a unique atmosphere. Unlike other islands, a conscious effort has been made to protect it,'' said Maria King Constantinides, a Boston antiques dealer with a family home there.

Signs in Greek, French, German or English scattered around the island's beaches point out that nudity is not allowed. One disco operates on a remote bay, but the narrow alleys around the monastery fall silent by 10 p.m., even in summer.

''People sometimes go topless on the beaches, but ... on the whole the rules are respected,'' said Christos Kyrozis, the island's doctor and also its mayor.

The development project planned by Greece's state tourist organization EOT, together with the monastery and town authorities, calls for construction of an airport, zoning for new hotels and bungalows and improved harbor facilities.

''Past experience shows that once an island gets an airport, mass tourism is very difficult to avoid,'' said Eleni Bonou, who heads the project. ''But an airport is essential because it serves the islanders first.''

More than 30,000 visitors come to Patmos every year, but two-thirds of them arrive aboard cruise ships that steam away before sunset after a few hours' stay.

On an island too barren to grow its own food, visitors are the only source of income apart from fishing.

''There's a delicate balance to be kept between God and mammon on this island,'' Mayor Kyrozis said. ''There has to be tourism, but not so much it kills what we have to offer.''

Trained for a more secluded life, the monks say it's already hard work taking turns to supervise the tourists swarming through the monastery museum, its frescoed chapels and stone colonnades.

''The sheer numbers of people coming through mean that we're exhausted by the time the season's over and there's time to get on with our own tasks,'' said Brother Chrysostomos, the monastery librarian.

The tourists also crowd into the Monastery of the Apocalypse, built over the cave where St. John supposedly wrote his visionary work while exiled on Patmos around A.D. 95.

''It's historical fact that St. John was on the island,'' said Athanassios Kominis, an Athens University professor of Byzantine studies. ''The tradition that he wrote Revelation there is certainly more than speculation, but not quite certainty,''

Patriarch Dimitrios, spiritual leader of Eastern Orthodox Christians worldwide, plans to lead Orthodox, Roman Catholic and Protestant churchmen in a two-day international pilgrimage to Patmos Sept. 25-26.

It celebrates the 900th birthday of the Monastery of St. John, founded in 1088 by a Byzantine scholar, the Blessed Christodoulos with special permission from the Emperor Alexius Comnenos.