The boat's sinking off Libya in April 2015 left as many as 800 people dead in the worst maritime tragedy in the Mediterranean since World War II. Italian Prime Minister Matteo Renzi has vowed to give all of the victims decent burials as a way of highlighting the human cost of the ongoing migrant crisis on Europe's southern shores.

The delicate operation to lift the vessel undamaged from 380 metres (1,245 feet), which began on May 11 but was repeatedly hampered by poor weather conditions, was completed on Monday, the navy said in a statement. A squad of fire service experts boarded the boat as it was being towed to Sicily to carry out the first assessment of accessible areas.

At the port of Augusta, the boat was to be placed inside a refrigerated tent 30 metres long, 20 metres wide and 10 metres high. Forensic experts will then begin the task of trying to identify the bodies prior to their burials, the navy said.

Fingerprints, DNA samples and distinguishing body marks are to be placed on file in the hope that the data may be of help to relatives seeking missing loved ones.

Abandoned on high seas

The disaster happened when a converted wooden fishing trawler packed with migrants collided with a Portuguese merchant ship that had responded to its SOS signal. The impact caused panicked passengers to surge to one side of the boat and it keeled over before sinking quickly in pitch darkness.

Only 28 people survived and some of them told rescuers that around 800 people had been crowded on board when it left Libya bound for Italy. Fifty bodies were recovered after the accident and another 171 since then from around the wreck, suggesting the remains of as many as 600 people could be onboard. Authorities are due to brief the media on the whole operation on Thursday.

More than 10,000 people have died in the Mediterranean since the current migrant crisis erupted in mid-2013. Aid agencies say it is likely many more have disappeared without a trace after being abandoned on the high seas by traffickers.

The complex and costly salvage operation was conducted by diving and marine company Impresub and heavy lifting specialists Fagioli under the supervision of the navy.

The companies used a specially designed robotic device with hydraulic arms and underwater cameras to lift the wreck without damaging it.

All apertures on the boat had been sealed off and some parts removed to ensure none of the bodies could fall out during the lifting onto a barge which was towed to Sicily by the Ievoli Ivory, an offshore tug ship.