Stink over sewage in the grotty Grotto of Capri

Two German spinsters giggle nervously as the swarthy young Neapolitan orders them to duck their heads and manoeuvres his wooden rowing boat through the narrow entrance to the cave. Once inside he abandons his broken German and breaks into "O Sole Mio" which echoes raucously around the dark cavern, lit only by the translucent turquoise light that radiates up from below the water. His oar narrowly misses the heads of a couple of bikini clad British girls who've plunged in for a dip.

Two German spinsters giggle nervously as the swarthy young Neapolitan orders them to duck their heads and manoeuvres his wooden rowing boat through the narrow entrance to the cave. Once inside he abandons his broken German and breaks into "O Sole Mio" which echoes raucously around the dark cavern, lit only by the translucent turquoise light that radiates up from below the water. His oar narrowly misses the heads of a couple of bikini clad British girls who've plunged in for a dip.

It's business as usual at "la Grotta Azzurra", the symbol of the Italian island of Capri and one of its main attractions. The water lapping the immense limestone cliffs looks clear enough but an untended leak in a sewage outflow pipe nearby is threatening not just the famous cave but the island's reputation as a natural paradise.

Two weeks ago photos printed in the local paper showed the normally crystalline waters cloudy and turgid with an ugly white froth and soda-like bubbles surging up from below the surface. The tide edged the sludgy mess to within a few yards of the Grotta Azzurra. The sight prompted a blitz by the provincial environmental safety authorities whose manager Luca Stamati described the situation as "dramatic". Laboratory tests revealed a presence of faecal bacteria 825 times the maximum safety limit.

"It's nonsense invented by environmental terrorists," says one of the oarsmen. "I swim every day and look how healthy I am." But local campaigners say the visibility of the sewage slick depends on time of day and the tides.

The nearby town of Anacapri, the less glitzy but equally snobbish alternative to Capri town, is responsible for the waste flow affecting the Grotta Azzurra. But its mayor, Franco Cerrota, is unperturbed.

"These results are scientific nonsense, the tests were carried out two days after the samples were taken and in that time any bacteria multiply exponentially. Further tests carried out last Thursday will prove that there is no problem at all," he predicts.

"The pipeline that carries treated waste out to sea had a crack, at a depth of about 100ft, and we are fixing it. These pipes are getting old, these things happen," he says philosophically, before admitting that the outlet pipe was damaged in a heavy storm at the end of December and won't be repaired until mid-June.

Further sewage problems on land create a stench that periodically wafts across the Marina Grande, the port where each day some 10,000 visitors, from industrialists on immense launches to day trippers on ferries, disembark to discover the island whose beauty so struck the debauched Roman emperor Tiberius that he ran the empire from here. Local paper, il Corriere del Mezzogiorno, headlined provocatively "Capri stinks - go home!" as it drew attention to the environmental neglect on the Mediterranean holiday spot.

Capri's rugged beauty and temperate climate have long made it a magnet for visitors and an inspiration for writers but its fame was consolidated in the Fifties when Hollywood stars and European royalty were among those frequenting its coves, seafood restaurants and be-seen cafes on the tiny Piazzetta, the chic drawing room of Capri. Habituees of the island include Naomi Campbell and her on-off Italian flame Flavio Briatore. Paparazzi last week were busy stalking Mariah Carey.

Costantino Federico, mayor of Capri town, does not even see the necessity for the two waste treatment plants that are being built on the island to comply with EU regulations.

"If it were not for the new law we would not need them as there is no industry or factories and the only problem is organic waste which when pumped out to sea at sufficient depth, 200ft, and distance, 2,000ft, from the coast is more than satisfactorily treated in the sea itself," he says blithely.

"I had friends here last week and they were shocked" says Mario Abate, a lawyer who commutes between Capri and Milan. "Their reaction was: 'Beautiful for walking, but we'll pass on the swimming, thanks.'

"I work with the world of fashion and people are ringing to query whether they should cancel trips or events here. The administrators think simply in terms of image and turnover, it doesn't occur to them that people could catch diseases."