Italian naval and coast guard vessels recovered 14 bodies and rescued around 200 people after a migrant boat sank in the sea between Libya and southern Sicily, authorities said.
Libya's navy has also said it intercepted and rescued 340 illegal migrants off the coast of the western town of Sabratha when their boat began to take on water in a separate incident.
The migrants were taken to a school near Zawiya, west of Tripoli, before being transferred to detention centres elsewhere in the North African nation, an AFP journalist said.
Among the rescued migrants were 40 women and 13 children, most of whom were Sudanese and Eritreans.
Both these incidents come a day after it was revealed dozens of people were drowned in a similar incident off the Libyan coast.
Italy has struggled for decades with a stream of migrants travelling in small, unsafe boats from North Africa to the islet of Lampedusa, midway between Tunisia and Sicily.
The influx of migrants has grown since the Arab Spring upheavals of 2011 and the protracted civil war in Syria.
An Italian navy statement said two naval and two coast guard patrol boats and a vessel from the Guardia di Finanza customs police had joined the rescue operation and medical assistance was being provided to survivors.
It was unclear how many other survivors or bodies might remain in the water, with some Italian media reports saying the boat may have been carrying as many as 400 people when it sank some 60 miles off the Libyan coast.
Hundreds of migrants were drowned in two separate disasters last year that prompted the Italian government to step up air and marine patrols of the seas south of Sicily.
Well over 25,000 migrants have reached Italy in the first few months of this year, with the collapse of order in large parts of Libya leaving authorities struggling to combat the groups that control the illegal migrant traffic.
"There has been an unexpected wave of illegal immigration these days and we do not know the reasons why this has happened yet," said Libyan Navy spokesman Colonel Ayoub Qassem.
With less than two weeks to go before European parliamentary elections, the issue of immigration has become a hot political topic, with Italian politicians repeating longstanding calls for other countries in Europe to do more to help.
"There needs to be urgent action by the European Union to open reception camps managed directly by the United Nations for refugees in Libya," Khalid Chaouki, an immigration specialist from Prime Minister Matteo Renzi's centre-left Democratic Party.
However, Italy's anti-immigration Northern League party repeated its call for the Mare Nostrum naval task force set up last year to be scrapped, saying it encouraged people smugglers.
"The Mare Nostrum operation is false charity, Russian roulette disguised as a humanitarian operation," said Gianluca Pini, a lawmaker from the party.