Italy has released the first photos of a migrant boat carrying about 750 people that sank in the Mediterranean in April killing almost everyone on board.

The images were taken by two navy minesweepers that successfully located the fishing vessel's wreckage in deep waters off Libya's coast.

Prosecutors leading the investigation into the tragedy from the Sicilian city of Catania said numerous bodies could already be seen trapped inside the hull and the lower bridge, Ansa news agency reported.

Only 28 were pulled alive from Mediterranean waters after the overcrowded smuggler boat allegedly crashed into a rescue vessel and sunk on 18 April.

Survivors told authorities the ship went down because of a hasty manoeuvre by the suspected captain, Mohammed Ali Malek, a 27-year-old Tunisian national, who survived the incident and has been arrested.

Malek allegedly steered the vessel into a Portuguese-flagged container carrier, the King Jacob, which had been dispatched by Italy's Coast Guard to rescue the migrant boat.

The collision destabilised the 20m (66ft) vessel, pushing migrants to rush to one side trying to get off, eventually causing the boat to capsize.

Damages to the bow and stern of the ship seen in the photos taken by navy vessels Gaeta and Vieste confirmed witness accounts, Catania prosecutors said.

The sunken ship was located after days of research at 375m of depth about 100km north of Libya.

The tragedy sent European countries scrambling to find new joint responses to the booming number of asylum seekers that attempt crossing the Mediterranean mainly from Libya and Egypt on a daily basis.

At an emergency summit in Brussels EU leaders decided to triple funding for rescue operations in the Mediterranean.

According to estimates, more than 250,000 migrants have successfully reached Europe via boat over the past 15 months. Another 5,000 are believed to have died trying, of which 1,700 perished in the first four months of 2015 only.

In March, the European Union's border agency chief warned up to one million migrants are expected to attempt crossing the Mediterranean from Libya before the end of 2015.