Italian authorities have intercepted some 800 migrants trying to cross the Mediterranean as EU leaders meet in Brussels to discuss the problem.
Dozens of women and children were among more than 200 migrants on one boat found in difficulty 25 miles (40km) south of the island of Lampedusa.
Two other boats were picked up further south of Lampedusa, one with nearly 100 Eritreans reportedly on board.
Hundreds of migrants trying to reach Europe have drowned in recent weeks.
Southern EU states including Italy and Malta have relaunched appeals for more support and resources, prompting the European Commission to call on EU countries to offer "additional and urgent contributions".
The Commission is pressing for:
- Greater resources to survey and patrol sea routes, through its Frontex operation
- Increased co-operation with countries of origin and transit, especially Libya
- The opening of more channels of regular migration
- Moves to spread migrants more evenly across the EU
However, national governments point out there are significant obstacles to some of these ambitions - including the lack of a stable government in Libya.
European Council President Herman Van Rompuy said on Friday that EU leaders all agreed that "determined action should be taken in order to prevent the loss of lives at sea".
But he noted that migration flows were "complex phenomena".
"We want to continue to address the root causes of illegal migration flows, working with countries of origin and transit, and this includes EU development support and a wider political dialogue with third countries," he said at a summit press conference.
German Chancellor Angela Merkel said short-term measures should be taken in Lampedusa, and that discussions about an EU migration task force and EU border agency Frontex would be continued at another summit in December - but long-term policy would be addressed only next year.
She said she did not expect a "sea change" in the way Europe deals with asylum-seekers.
EU sources say leaders want to see a new surveillance effort, Eurosur, come into force, before committing more money or resources.
Maria Nicolini, the mayor of Lampedusa, the Italian island where many of the bodies have been brought ashore, was in Brussels to lobby EU leaders.
Many of the migrants who try to cross the Mediterranean come from developing countries afflicted by poverty and conflict, such as Syria and Eritrea.
The UN special rapporteur on human rights in Eritrea said on Thursday that thousands Eritreans were fleeing their country every month, despite a "shoot-to-kill policy" targeting those attempting to leave.
The envoy, Sheila Keetharuth, said Eritreans were subject to "the most serious human rights violations", including extra-judicial killings, torture and inhumane prison conditions.
She said that according to UN figures, 7,504 Eritreans and 7,557 Syrians had arrived in Italy in the first nine months of the year.
Boats, often operated by trafficking gangs, have been attempting the crossing to Europe for many years.
But the issue was brought to the fore earlier this month when more than 350 people - mostly Somalis and Eritreans - died after their boat sank off Lampedusa.
"Europe can neither save nor welcome the whole world," European Parliament President Martin Schulz told the EU summit.
"But we are the world's richest continent and so must do more, especially if we act together, seek solutions together, and together take responsibility."