Italy has begun to salvage the bodies of people killed in the Mediterranean’s deadliest modern shipwreck, in an operation that experts say is of historic scale.

The Italian navy has pulled the boat to the surface, more than 14 months after it sank in April 2015, killing about 800 people who were sailing from Libya towards Italy to seek asylum.

The boat was being towed on Wednesday to the Sicilian port of Augusta, where it will be kept in a refrigerated container while the bodies still inside are removed and taken to a nearby morgue.

Over the past year, 169 bodies have been recovered from near the boat, which has been sitting 370 metres below sea level, 85 miles north of Libya, since last April.

For the first time, experts can now try to identify those who were unable to escape the boat as it sank, and to count the number of bodies.

“This is one of the largest events of its kind, if not the largest,” said Dr Cristina Cattaneo, the head of a team of 50 pathologists tasked with identifying the corpses. “We expect between 400 and 600 [bodies].”

Facebook Twitter Pinterest Around 800 migrants and refugees are believed to have drowned when their boat capsized. Photograph: HO/AFP/Getty Images

Speaking as she left for Sicily, Cattaneo added: “The bodies are still in the ship. The ship is going to be brought into a refrigerated area, and from there the bodies will be brought to a nearby morgue.”

Only 28 people survived the disaster, after the smuggling boat – a re-purposed fishing trawler – hit a merchant vessel that had been sent to rescue it, then sank. Some of those packed on to the upper decks of the boat were able to jump into the water, while one survivor interviewed by the Guardian last year said he had been able to jump straight into the merchant ship.

But most passengers were trapped below decks, and were unable to escape once the water flooded in. According to one of the few who managed to escape these cabins, people desperately grabbed on to what they could. “Someone grabbed my trousers because they couldn’t swim,” said Ibrahim Mbalo, a Gambian survivor, during an interview last year. “I thought: will I die? Or will I survive?”

Mbalo only escaped after wrestling free of the man’s grip, and swimming through one of the only openings in the cabin. By his estimate, he spent three or four minutes under water.

The disaster came in a week when an estimated 1,200 people drowned between Libya and Italy, sparking a public outcry in Europe that prompted EU leaders to restart full-scale rescue operations in those waters.

Politicians had previously argued that the rescue operations acted as a pull factor, and had refused to re-instigate them following their ending in late 2014.

About 150,000 people, mainly sub-Saharan Africans, travelled to Italy by this route in 2015. Migrants are reaching Italy at roughly the same rate in 2016.

Some 850,000 people, mainly Syrians and Afghans, reached Greece by boat in 2015, but their numbers have dropped off in 2016 following the implementation of the EU-Turkey deal.