The captain of an NGO involved in one rescue said that finding survivors from a shipwreck off the coast of Italy, where dozens of migrants are dead or missing, involved walking through corpses to find those who were barely alive.

A boat carrying 51 survivors and ten bodies was intercepted approximately 90 km (56 miles), south of Lampedusa. Another was found about 200 km east of Calabria in southern Italy.

On Monday, 11 survivors of the second shipwreck, along with the body a woman, were brought ashore. According to aid groups, 64 people were still missing, including 26 children. The Italian Coast Guard recovered three additional bodies on Tuesday.

Ingo Werth, captain of the German aid group RESQSHIP which operates the Nadir boat, was the first to rescue the 51 survivors in the early morning hours of Monday. He said that the boat had been "totally crowded" with wooden boats.

His team checked the lower level before leaving and discovered what appeared to be about 12 bodies. The medical officer said: "There's someone who is breathing. He makes noise. I hear noise."

Crew members donned gas masks and went down to the bottom to rescue him. A second inspection revealed another survivor, but it was difficult for the nurse and captain to get him out.

Werth said, "The boat (of migrants) was close to capsizing. It was therefore a grave for rescuers."

The nurse and captain left the hold to go above deck. They managed to pull the man through the hole that was made above the man's head with an axe.

Werth, referring to the survivors with a hand sign to indicate they were near death, said "There was still that much life in them both". The body temperature of one of the survivors was lower than 32 degrees, he said.

He added that the pair had been airlifted by helicopter to a hospital near Palermo, where they are now recovering.

Two shipwrecks in the central Mediterranean have confirmed its reputation as one the most dangerous migration routes. U.N. statistics show that more than 23,500 migrants died or went missing in the central Mediterranean since 2014.

According to RESQSHIP the migrants picked up in the south of Lampedusa left the Libyan port Zuwarah after spending two days on the sea. Rescuers were told that half the passengers were from Bangladesh and others were from Pakistan, Syria, and Egypt.

According to the U.N. and Doctors Without Borders charity, the migrants who sailed from Turkey and spent eight days on the sea came from Iran and Syria. They also had ties with Iraq, Afghanistan and Iraq.

The survivors are "very confused", and they don't "know who among their family members is still alive or dead on the sea". Whole families have been destroyed. Cecilia Momi, an MSF employee, said that some families have lost their wife, child, husband, friend, or grandchild.