Man held in Italy jail for 18 years killed in Somalia blast
"We have rescued 48 people alive from the sea while 15 bodies have been spotted by the crew of the helicopter," coast guard spokesman Vittorio Alessandro, based on the southern Italian island of Lampedusa, told AFP.
Around 130 people who were on the boat are believed to be missing.
"We are still hoping. Our boats and helicopters have thrown all sorts of lifejackets and lifeboats to allow people to hold on," Alessandro said.
Coast guards said in a statement that the boat was 13 metres long and had departed two days ago from the town of Zuwarah in western Libya. The statement said the people on the boat were mostly Eritreans and Somalis.
Hundreds of African refugees from Libya -- many of them migrant workers stranded after the start of an uprising against Libyan leader Moamer Kadhafi and the beginnings of a civil war -- have landed in Italy in recent days.
More than 20,000 migrants fleeing continuing unrest in Tunisia have also arrived on Lampedusa, sparking a humanitarian emergency.
Migrants and refugees often travel in rickety and overcrowded fishing boats and there have already been smaller accidents at sea.
The tiny island of Lampedusa is closer to North African shores than to mainland Italy and has become a gateway for illegal immigration into Europe.
Italian media reported that a coast guard vessel with those refugees rescued from the disaster was set to arrive on the outcrop imminently.
"They are not in serious condition but they need attention," Alessandro said.
The accident happened some 40 nautical miles (46 miles, 74 kilometres) south of Lampedusa in waters that are under the jurisdiction of Malta.
A fishing boat is also taking part in rescue efforts, the coast guard said.
A distress signal from the refugee boat was received overnight by Maltese authorities and officials in Lampedusa thanks to a satellite phone on board.
No group has claimed responsibility for his murder, but such incidents bear all the hallmarks of past attacks in Somalia by Al-Shabaab militants.