4,200 more rescued, 17 found dead

The Italian coastguard said it had coordinated the rescue of about 4,200 migrants sailing across the Mediterranean Sea on Friday, but also found 17 corpses on several of the rickety boats.

Distress calls were made from 22 different boats, many off Libya but also off the southern Italian coast.

The total number of people rescued in 24 hours is one of the highest in recent years but the coastguard could not confirm if it was a record. So far, the busiest days this year have been the rescue of 3,791 migrants on April 12 and 3,690 on May 2.

The 17 bodies were found on three inflatable dinghies, from which more than 300 other migrants were rescued alive.

Another maritime rescue mission on Thursday saw more than 700 migrants rescued off  Sicily coast.

Overall, more than 40,400 boat 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.