Italian police said Wednesday they had arrested a survivor of a migrant shipwreck that left dozens of people dead, accusing him of murdering a teenage Iraqi girl on board.

The AGI news agency reported the man, also Iraqi, had been raping the girl when she died, although a police spokesman would not confirm this to AFP.

In a statement police said the sailing boat was adrift off Italy when the man "vented his aggression on a 16-year-old Iraqi girl, the daughter of another survivor, leading to her death by suffocation".

Twelve people were rescued from the ship, which police say is believed to have been carrying around 70 people.

The ship originated in Turkey and was wrecked about 120 nautical miles off the southern coast of Italy.

The survivors were brought to the port of Roccella Ionica on June 17. However, one of them, a woman, then died.

Another 35 bodies were subsequently recovered from the water in search efforts, local authorities said Tuesday -- bringing the toll to 36.

The bodies found at sea included 15 minors.

The survivor accused of murder has been detained in prison in Catanzaro, the capital of the Calabria region, police said.

Security forces in Iraq's Kurdistan on Tuesday announced the arrest of four suspected human traffickers over the shipwreck.

According to non-governmental organisations and accounts from victims' families, the sailing boat was carrying mostly Kurdish migrants from Iraq and Iran, along with Afghan families.

The UN's International Organization for Migration says about 3,155 migrants died or went missing in the Mediterranean last year and more than 1,000 people so far this year.

The Central Mediterranean migration route, on which Italy lies, is the deadliest in the world and accounts for 80 percent of the deaths on that sea.

Thousands of migrants depart from Libya and Tunisia by boat towards Europe, with Italy often the first landing point.