New distress calls have been received from migrant boats in the Mediterranean, as EU ministers met in Luxembourg to discuss the crisis.
Italy and Malta said they were working on rescues of at least two boats in distress with hundreds on board.
The EU added the migrants issue to its agenda after a boat sank early on Sunday with hundreds feared drowned.
EU ministers are under pressure after last year’s decision to scale back search-and-rescue efforts.
Italian PM Matteo Renzi said on Monday that his country was working with Malta to rescue at least two boats in distress.
He said one of the vessels was a dinghy off the Libyan coast with about 100-150 people on board. The other was larger boat carrying 300 people.
The Maltese navy told the BBC that there were a number of new incidents involving rescues being co-ordinated off Libya by the Italians.
The International Organization for Migration (IOM) also said it had received a distress call from a boat sinking in the Mediterranean with at least 300 migrants on board.
The caller said about three boats needed help in international waters and 20 people had died.
But IOM spokesman Joel Millman told the BBC the organisation was still trying to verify the details and it was unclear whether the call was related to the Maltese and Italian rescues.
Earlier, the Greek coastguard said a vessel carrying dozens of migrants had run aground off the island of Rhodes. Three people were killed and 80 rescued, it said.
‘Human dignity’
Ahead of the Luxembourg talks, the EU’s foreign policy chief Federica Mogherini said Europe had a “political and moral duty” to act on the migrant crisis in the Mediterranean.
“The Mediterranean is our sea and we have to act together as Europeans… The European Union was built and is built around the protection of human rights, human dignity and the life of human people – we need to be consistent in that.”
The EU has been criticised since the rescue operation, Mare Nostrum, was ended last year amid concerns over cost and fears it was encouraging more migrants. It now runs a more limited border control operation called Triton.
German Chancellor Angela Merkel said she was “appalled” by Sunday’s disaster and wanted Europe to find “answers”, her spokesman said.
UK Prime Minister David Cameron said it was “a dark day for Europe”, adding that “search and rescue is only one part. We need to go after traffickers, help stabilise these countries”.
Mr Cameron spoke to Mr Renzi by phone on Monday and backed the Italian PM’s call for an emergency European Council meeting on the migrant crisis.
Human smugglers are taking advantage of the political crisis in Libya to use it as a launching point for boats carrying migrants who are fleeing violence or economic hardship in Africa and the Middle East.
In a joint press conference with Maltese PM Joseph Muscat in Rome, Mr Renzi said the priority was to stop the traffickers at source.
However, he said military intervention in Libya was “not on the table”.
Mr Muscat said Sunday’s disaster off Libya, in which only 28 of some 700 migrants were rescued, was “a game changer”, adding: “If Europe doesn’t work together history will judge it very badly.”
The UN says the route from North Africa to Italy and Malta has become the world’s deadliest.
Up to 1,500 migrants are now feared to have drowned this year alone.
Source: BBC