German charity RESQSHIP said it picked up 51 people from a sinking, wooden boat and found 10 bodies trapped on the lower deck near the island of Lampedusa on Monday, BBC reported.
In a separate incident on the same day, more than 60 people were reported missing, with 26 of them feared to be children, Médecins Sans Frontières (MSF) said.
The boats were carrying migrants who had set off from Libya and Turkey, UN agencies said.
Survivors of the shipwreck near Lampedusa were handed over to the Italian coastguard and taken ashore on Monday morning, while the deceased were being towed to the island, according to RESQSHIP.
The boat had set off from Libya, and was carrying migrants from Syria, Egypt, Pakistan, and Bangladesh, the UN refugee agency UNHCR, the International Organization for Migration (IOM) and UN children's agency UNICEF said in a joint statement.
The other shipwreck was located about 125 miles off the coast of Calabria in southern Italy, the agencies said.
One of the surviving 12 people died after disembarking, the Italian coastguard said.
The Mediterranean is the deadliest known migration route in the world.
More than 23,500 migrants have died or gone missing in its waters since 2014, according to UN data.
SD/PR