According to Save the Children aid group, dozens of migrants have drowned in the Mediterranean after a boat carrying an estimated 137 people sank south of Sicily.
The NGO says survivors reported up to 40 people fell into the sea as a rescue vessel was approaching.
The survivors arrived in the city of Catania on May 5th.
At least 1,750 people have died this year trying to cross the Mediterranean, a 20-fold increase on the same period in 2014.
Save the Children’s representative in Catania Giovanna di Benedetto said the latest sinking is thought to have happened on May 3rd, but the exact toll was not known.
“They [survivors] said there were 137 people aboard an inflatable boat that deflated or exploded – it wasn’t clear – and that some of them fell overboard,” Giovanna di Benedetto told AFP news agency.
“Some said <<very many>> died, others said <<around 40>>,” she added.
The survivors were picked up by a Maltese merchant ship and five bodies were also recovered.
Dramatic footage of the rescue, obtained by The Associated Press, shows migrants desperately jumping off a deflating dinghy, and trying to climb up ropes and a rope ladder to the merchant ship.
About 100 people were found on a second boat, with no deaths reported, the aid agency added.
The number of migrants attempting to make the perilous journey across the Mediterranean has risen in recent weeks as smugglers take advantage of fair weather.
In the past three days about 7,000 people have been rescued and 10 bodies recovered off the Libyan coast, according to the Italian coastguard.
Italian and French ships picked up survivors from wooden and rubber boats on at least 17 separate operations.
Meanwhile Turkey’s coastguard on May 5th said it had rescued more than 600 people trying to cross the Aegean Sea in the past week, Reuters reports.
More than 400 were men, women and children fleeing Syria, while the rest came from Iraq, Afghanistan, Myanmar (Burma) and various African countries, the office of the Izmir provincial governor is quoted as saying.
The latest deaths come as naval chiefs from 26 European countries are due to discuss the migrant crisis at talks in Naples, southern Italy.
EU nations agreed last month to triple funding for rescue operations run by European border agency Frontex, contribute more boats and patrol aircraft for rescue efforts, and look at ways to target smugglers’ boats with military strikes.
A state of emergency has been declared in Sicily because of the large numbers of African migrants it has to deal with.
According to the Italian navy, almost 300 migrants have been rescued from two boats near the island of Lampedusa in the waters between Libya and Sicily.
The first, about 60 miles to the south of Lampedusa, was carrying 80 migrants, a navy statement said.
The second, said to be at danger of sinking was carrying 210 people.
It was 45 miles from the island.
A state of emergency has been declared in Sicily because of the large numbers of African migrants it has to deal with
The latest rescues come a day after Italy announced increased patrols following the deaths of hundreds of migrants sailing in overcrowded boats.
The migrants were all being transferred to Lampedusa, the navy said.
On Friday, at least 33 people died when their boat capsized between Malta and Lampedusa.
A week earlier, more than 350 migrants died in another shipwreck off the island, one of the deadliest such incidents in recent years.
Italy has previously called for EU help in dealing with the thousands of desperate migrants who wash up on its beaches every year.
Many are families fleeing war and poverty in Africa and the Middle East who hope for a better life in Europe.
The recent loss of life has led to further calls for EU action.
On Monday, Italian Defense Minister Mario Mauro said the country intended to triple its presence in the southern Mediterranean.
“We need strong action to stop these shipwrecks,” he told Italian newspaper Avvenire.
In addition to coastguard and border police vessels, the Italian navy currently has three ships supported by four helicopters patrolling the area. It can also call on two surveillance aircraft with night-vision capabilities.
According to the UN, some 32,000 migrants have arrived in Malta and Italy this year.
At least 130 migrants have died and many more are missing after a boat carrying them to Europe sank off the southern Italian island of Lampedusa.
A total of 103 bodies have been recovered and more have been found inside the wreck, coast guards say.
The African migrants reportedly threw themselves into the sea when a fire broke out on board. More than 150 of the passengers have been rescued.
Most of those on board were from Eritrea and Somalia, said the UN.
The boat was believed to have been carrying up to 500 people at the time and some 200 of them are unaccounted for.
At least 130 migrants have died and many more are missing after a boat carrying them to Europe sank off the southern Italian island of Lampedusa
Italian Interior Minister Angelino Alfano said the ship had come from Misrata in Libya and began taking on water when its motor stopped working.
It is thought that some of those on board set fire to a piece of material to try to attract the attention of passing ships, only to have the fire spread to the rest of the boat.
It is one of the worst such disasters to occur off the Italian coast in recent years; Italian PM Enrico Letta tweeted that it was “an immense tragedy”. The government has declared a day of national mourning on Friday.
“There is no miraculous solution to the migrant exodus issue,” said Italian Foreign Minister Emma Bonino.
“If there were we would have found it and put it into action.”
In a separate incident on Thursday, local media reported that around 200 migrants were escorted to the port of Syracuse on the island of Sicily, when their vessel encountered difficulties five miles off the coast.
Earlier this week, 13 migrants drowned while trying to reach Sicily.