Why the Mediterranean death toll is surging

It is not just the scaling back of Italy's naval search and rescue operation that has led to this year's surge in the number of people drowning in the Mediterranean as they seek to reach Europe from north Africa.

At least 1,750 asylum seekers or migrants have perished in the waters between Libya and Italy since the turn of the year, 30 times the total registered in the same period of 2014.

But the dramatically higher death toll does not reflect more people risking their lives to get to Europe: the numbers arriving in Italy are broadly flat -- 22,000 up to April 20, compared with 26,600 for January-April 2014, according to the International Organisation for Migration.

"The boats are getting more clapped out and more packed at the same time," IOM spokesman Flavio di Giacomo told AFP. "Whether it is wooden fishing boats or rubber dinghies, the one thing they have in common is that they are always very, very old."

"After a few hours at sea, they start to take on water. That is why it is getting harder and harder to rescue them."

When an Italian coastguard vessel disembarked at Augusta in Sicily last week with 600 migrants rescued from five different boats over the course of two days, the aid workers at the scene all acted as it had been a totally routine operation.

But in reality each of the five incidents involved boats that came perilously close to sinking, according to the migrants on board.

"The water started coming in. We called for help at 1:00 p.m. and then we waited, and waited," recounted Malik Tourey, a Nigerian who was on board one of the vessels.

"We had to bail out the boat, everyone together, everyone shivering, women crying. It wasn't until 3.00 a.m. the following day that the coastguard arrived."

30cm wave enough

Italian navy captain Michele Maltese, a spokesman for the coastguard based at Catania on Sicily's eastern coast, said the boats used by people smugglers have always been barely seaworthy.

"What is happening now is they are having more and more people packed onto them," he told AFP.

"On a fishing boat designed for a crew of ten, the traffickers find a way to squeeze between 400 and 500 on board. They become so unstable that a 30-centimetre (one-foot) high wave is enough to result in them taking on water," he said.

"Every boat that puts to sea is doing so at a very high risk (of sinking)."

The traffickers are so cynical they sometimes charge their passengers extra for a life jacket. Maamadou Dialo, who arrived earlier this month, was among those who stumped up, but soon discovered it was far from sound investment. "It must have been made in China - after five minutes in the water you would have sunk!"

Maltese said Italian authorities tried to ensure traffickers' boats were confiscated and destroyed in Italian ports. But difficult sea conditions meant that was not always possible in the heat of a rescue operation and many are left to drift.

"Human safety is our priority," the coastguard said.

Twice this year traffickers have threatened Italian coastguards with weapons in order to recover and reuse boats from which the human cargo has been taken to safety.