Italian warships rescued 290 migrants in the Mediterranean on Tuesday and Sicily declared a state of emergency as Rome launched a huge patrol operation to scare off people-smugglers.

Drones, warships and helicopters were deployed inside and outside Italian waters following two tragic shipwrecks this month in which more than 400 Eritrean, Somali and Syrian refugees drowned.

Hi-tech radars and night-vision equipment are also being used by Italian forces in the operation, named Mare Nostrum (Our Sea) -- the term used by the ancient Romans to refer to the Mediterranean.

The navy has dispatched five warships to patrol what Italian Prime Minister Enrico Letta has called the "sea of death", and said on Tuesday that it had rescued 290 migrants near the island of Lampedusa, Italy's southernmost territory.

An Italian cargo ship also helped the Greek coastguard rescue 73 Syrians stranded on a yacht in the Ionian Sea after it ran out of fuel.

And a Panamanian merchant vessel picked up about 80 people adrift on a large raft in Libyan waters and took them to Sicily, the coastguard said.

Following a call for aid via satellite phone, the Italian coastguard asked a Liberian merchant ship to change course to help about 100 people in Libyan waters, while another ship came to the aid of a dinghy with 90 people on board in Maltese waters.

Sicily's regional assembly meanwhile approved an emergency decree that governor Rosario Crocetta said would speed up security measures to deal with the growing influx of refugees on the island.

The latest arrivals come on top of the 32,000 asylum seekers that the United Nations refugee agency says have landed in Italy and Malta so far this year.

Most leave from an increasingly lawless Libya and arrive on tiny Lampedusa, where the local refugee centre is often severely overcrowded.

Border guards said on Tuesday they had also seized a "mother ship" and arrested 17 crew members, who are believed to be Egyptian, following a landing in the southern Calabria region on Sunday.

These larger fishing vessels are often used by smugglers to carry out most of the journey. Migrants are then put on smaller boats when they are nearer the coast to evade controls.

Thousands have perished over the years as the crossings are often made on ageing vessels.

The refugee shipwreck on October 3 off Lampedusa was the country's worst ever, with 364 people killed when their 20-metre boat caught fire, capsized and sank within sight of the shore.

Just a few days later another heavily laden boat flipped over in rough seas off Malta, killing at least 36 of the Syrian refugees on board.

Maltese Prime Minister Joseph Muscat said the final toll could be "between 50 and 200".

'Stop people dying at sea'

European Union Home Affairs Commissioner Cecilia Malmstroem has said the EU border agency Frontex should deploy a vast maritime search-and-rescue operation from Cyprus to Spain.

But experts say stepped-up security at sea could leave thousands of migrants stranded in north Africa at the mercy of militias and traffickers and reinforce a "Fortress Europe" mentality.

Experts also say it will be difficult to persuade EU governments to finance a major patrol or agree to a European border control, particularly in recession-hit countries or where anti-immigration sentiment is on the rise.

"Search and rescue is good in principle, but it touches on sensitivities over relinquishing control of national waters," Elizabeth Collett, director of Brussels-based think tank Migration Policy Institute Europe, told AFP.

Collett said that beyond scaled-up patrols, Europe needed to address the more complex issues of dismantling smuggling rings and deterring people from attempting the perilous crossings.

Professor Alessandra Venturini from the European University Institute Migration Policy Centre said the priority was to "stop people dying at sea".

"Centres at transit points in Turkey and Egypt where people can make asylum requests could help reduce the numbers attempting to enter the EU illegally," she said.

Italy also wants a change in asylum laws that currently mean all asylum-seekers must stay in the European country where they first arrive while their application is considered.

Southern European countries like Italy argue this puts an unfair burden on them as the landing points, but northern European states argue they end up taking in most of the refugees.