Nearly 700 asylum seekers have been rescued off the Italian island of Sicily in the space of 24 hours, including dozens of Eritreans, officials said.

Italian coastguard and navy vessels, along with a Maltese cargo ship, helped save them from five boats in the stretch of water between Sicily and Tunisia.

Officials said at least two of the vessels were adrift, with dozens of women and children among those onboard.

"It was a night of rescues in the Strait of Sicily," the coastguard said in a statement.

Earlier this month 366 people were killed in a shipwreck just off the Italian island of Lampedusa, including many asylum seekers from Eritrea.

Some of the asylum seekers rescued between Thursday and Friday were also Eritreans.

The Italian government launched a massive search and rescue operation in response top the earlier tragedy and stepped up naval patrols.

Some 300 would-be migrants that were rescued were transferred onto an assault ship that is part of the operation.

In Brussels, EU leaders grapple with asylum seeker issue

The mayor of Lampedusa, the island where most asylum seekers land, warned European leaders meeting in Brussels of the need for an urgent rethink of immigration policies.

The 300-bed refugee centre on Lampedusa is currently housing 700 and more of those who were rescued are arriving.

Italian lawmakers say the squalid conditions in the centre are unacceptable.

"Unless Europe's approach to asylum and immigration changes, it won't only be the migrants but the European Union that drowns off Lampedusa," said Giusi Nicolini in Brussels, where she met with European Parliament head Martin Schulz.

Italian prime minister Enrico Letta has also pressed EU leaders to increase aid to Mediterranean countries including Italy, Greece and Malta which have handled the brunt of the crisis.

More than 33,000 would-be migrants have landed in Italy so far this year, nearly three times more than the number for last year.

The most common countries of origin are Eritrea and Somalia and now also Syria.

WIRES