Still scattered on the decks is what was left behind by those who made it ashore: odd shoes, discarded clothes and empty water bottles sloshing about in dirty, oily water. According to local fishermen, the migrants in these boats were brought in by the coastguards 10 days previously.

The terrible stench gives some idea of the ordeal they must have endured. 'When they arrive they are suffering from nausea, vomiting, sunburn, dehydration, hypoglycaemia, diarrhoea,' says Dr Claudia Codesani from the charity Médecins Sans Frontières.

'They have been at sea for 17 hours or for as long as five or six days and they are desperate to eat and drink. Everyone is shocked and frightened. Many of them say to me: "Where is the train station for Milan"?'

This tiny island 205 kilometres (about 127 miles) off the coast of Sicily and 113 kilometres from Tunisia doesn't even have a taxi, far less a train station. The people-smugglers who make small for tunes out of these clandestini, charging between €1,000 (£687) and €1,500 per person, know full well that the boats will not reach mainland Italy.

They crush in as many people as possible, give one of them a compass and direct him to steer due north. As they set off from Libya or Tunisia, the passengers are unaware they have only enough fuel to reach Lampedusa. Overcrowded and dangerously low in the water, these boats of misery limp along in the swelling waters of the Mediterranean until, if they are lucky, they are spotted by Italian coastguards.

At the headquarters of Lampedusa's Guardia di Finanza, the equivalent of Customs and Excise, Commander Cavallin and his men are enjoying a break from their daily routine of picking up survivors from the boats.

'When the sea consents, we can get 250 to 300 of these poveracci [pitiable people] a day,' he says. So far this year 4,500 migrants have landed at Lampedusa and the commander expects that the final tally for 2005 will be the same as last year - around 10,000. The record was 1,000 arriving in 48 hours.

It must be difficult work, intercepting these boats and dealing with such wretchedness every day. 'Yes, but you become used to it,' replies Cavallin, pointing to a plaque on his office wall. It is a commendation signed by President Carlo Azeglio Ciampi for a rescue a few years ago of a boatload of people in rough seas.

'There were a lot of dead people on that boat - 13 bodies,' the commander said. 'I found this girl and she was frozen, completely frozen, and near to death. I pulled her out and I warmed her with my own body to keep her alive.' She lived, but the officer and his men were quarantined for a month for fear of meningitis.

'You see the tears, the terror in their eyes - it is always a desperate situation,' he said. Once, he remembers, a woman and children were brought to the station to be questioned about their identity. 'My wife came by and brought some sweets and these children, six or seven years old, did not know how to open a sweet because they had never seen one before.'

Lampedusa (population 5,500) with its volcanic landscape, turquoise seas and stunning coves and beaches, has always been a magnet for tourists, mostly Italians who come from cities seeking a few days of sea air.

Bob Geldof enraged local people when he claimed on British television last month, before the Live8 concerts, that bodies of dead African children were washing up daily on Lampedusa's beaches.

This upset business people struggling to maintain Lampedusa's reputation as a resort and angered the men of the Guardia di Finanza who risk their own lives to save those in danger.

An unknown number of craft have capsized, their occupants drowned, but bodies do not wash up on the shore, says Cavallin. 'It's not true to say we are under siege here. It is bad for our business to give this impression,' said one hotelier.

Angela Maraventano, local secretary of the ultra-right Northern League party, says the impression that Lampedusa is bursting at the seams with illegal immigrants is wrong. She claims tourism is down 40 per cent this year because people believe the stories about bodies on the beaches.

'We are all frightened after what happened in London,' she says, referring to last week's bombings. 'We don't know who these people are and what their intentions are.'

Despite the improbability of terrorists arriving by rickety boats, Maraventano insists the immigrants could be a danger to the Italian way of life: 'We don't want them here, we don't know who they are and what they believe in. They should go back to their own countries.'

Once on dry land, the illegal immigrants are interviewed, fingerprinted and photographed. Prior to embarkation, they will have destroyed their documents and may claim to be from places such as Turkey, Kashmir or Palestine in the hope of improving their chances of gaining asylum.

Some of the clandestini who arrive on Lampedusa this year will be sent back to their own countries, but many will remain illegally in Italy or move on to other countries in Europe. They will have to pay their debts to the people-smugglers, and have little hope of finding the bright new lives they have dreamed about.

Those staying in Italy will probably be reduced to selling socks, scarfs and sponges from trolleys in supermarket car parks, or peddling fake fashion handbags on the streets of big cities and handing most of the money to someone else. Others will simply have to beg. One has to wonder if their terrible journeys were worth it.