The Italian Navy said that the 18 people found dead on board the overcrowded wooden vessel had probably died of carbon monoxide poisoning from engine fumes. The deceased were found crammed into the hold of the boat, along with three other very ill men who were rushed to the island of Lampedusa for treatment.

One of them died en route, the two others were later flown by helicopter to a hospital in the Sicilian capital of Palermo.

A Danish cargo ship spotted the 25-meter (82-foot) wooden vessel, carrying at least 400 people, on the border between Italian and Maltese waters, according to a statement from the coast guard. Maltese authorities requested help from Italy, and two other merchant ships also participated in the rescue.

Italian rescuers noted increased activity on the Mediterranean in recent days, owing to good weather, calm waters, and the increasingly unstable situation in Libya.

Thousands of people try to reach the European Union by boat from northern Africa, often embarking from Libya, hoping for asylum on arrival. Over the last three days, Italy's Navy said it had rescued more than 4,000 migrants, with a warship on Saturday arriving in the port of Salerno with 2,186 people from Egypt, Eritrea, Ghana, Somalia and Syria.

'Ever more perilous' conditions

More than 70,000 have been rescued so far this year by the Italian "Mare Nostrum" ("Our Sea") mission monitoring the popular crossings, compared to the previous record of just over 60,000 people for the entire calendar year of 2011.

"The conditions of these journeys are becoming ever more perilous and are killing dozens of people every day," Carlotta Sami, a spokeswoman in Italy for the UN's refugee agency, said on public news channel RaiNews24.

"Over the past 48 hours we have seen uninterrupted rescues by merchant vessels, military ships and the coast guard. There is a huge number of boats on their way."

Italy - along with Mediterranean EU members Spain, Greece and Malta - has been left largely on its own managing the growing number of migrants, partly because of increasing anti-immigrant sentiment in countries like France and Britain.

Italy seeks Frontex assistance

Italian Interior Minister Angelino Alfano has begun talks with EU Home Affairs Commissioner Cecilia Malmström on the possibility of sharing the load with other European Union members in a "scaled down" version of Mare Nostrum. The government in Rome would like the EU's Frontex border agency to coordinate the mission in future.

"We are taking important steps to make sure that all of Europe is present in the Mediterranean, and not just Italy," Alfano said on Saturday, suggesting that the new arrivals should not all remain in Italy, but rather be redistributed across the bloc. "We should not keep them here, because hardly any of them want to stay in Italy."

Human rights groups, such as Amnesty International, and Pope Francis have urged the EU to do more both to welcome the refugees and to stop them from resorting to dangerous sea crossings of the Mediterranean.

msh/ng (AFP, dpa, Reuters)