More than 4,200 migrants are being brought to southern Italy after being rescued from boats in the Mediterranean in just 24 hours, the Italian coastguard said.
The migrants were rescued from wooden fishing boats and motorised rubber dinghies on Friday and Saturday in operations involving ships from nations including Italy, Ireland, Germany, Belgium and Britain.
Distress calls were made from 22 different boats, many off Libya but also off the southern Italian coast.
Seventeen bodies were found off Libya on three inflatable dinghies, from which more than 300 other migrants were rescued alive, the Italian navy said on Twitter. Details of the nationalities of the victims and how they died have not yet been released.
The total number of people rescued in the past 24 hours is one of the highest in recent years. So far, the busiest days this year have been the rescue of 3,791 migrants on April 12 and 3,690 on May 2.
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Overall, more than 40,400 migrants - many of them fleeing conflict and poverty in countries such as Syria and Eritrea - have arrived in Italy since the start of the year, similar to the same period last year.
So far this year, about 1,770 migrants have perished on the hazardous journey to Europe, according to a latest International Organization for Migration (IOM) report which does not include the latest rescues, a 30-fold increase on the same period in 2014.
The huge spike in the number of people trying to cross the Mediterranean Sea in recent weeks has been attributed to the worsening security situation in Libya - the staging post for most of the crossings - as well as milder weather.
"It happens a lot in waves, you could have a few days where nothing happens, then there can be a high number of arrivals at the same time," Flavio di Giacomo, a spokesman for the IOM in Italy, told the AFP news agency.
After a string of deadly shipwrecks that sparked global alarm, EU ministers this month approved plans for a military operation to fight people smugglers in the Mediterranean, although proposals to destroy traffickers' boats in Libyan waters still need UN approval.
The European Commission also unveiled plans to make the rest of the 28-nation EU share the burden of frontline states such as Italy, Greece and Malta when it comes to taking in migrants, although some countries such as Britain are opposed.
While massive, this year's numbers are level with last year when authorities registered 41,243 arrivals between January and May 31.
A difference is however being felt in Greece which has registered 37,000 arrivals since the beginning of the year - already 3,000 more than in the whole of 2014, di Giacomo said.