Prosecutors said they had detained a Tunisian man believed to be the captain of the vessel and a Syrian allegedly a member of the ship’s crew, taken from a group of 27 haggard survivors who arrived in the Sicilian port of Catania on Monday evening.

The two were charged with people trafficking and the captain was also charged with reckless multiple homicide in relation to the sinking.

The arrests came after an emergency meeting of EU interior and foreign ministers in Luxembourg on Monday made a decision to launch military operations against the networks of smugglers in Libya, as well as to bolster maritime patrols in the Mediterranean and give their modest naval mission a broader search-and-rescue mandate for saving lives.

The Italian coastguard ship carrying the survivors arrived late on Monday night, with all the migrants on board disembarking by 1.45am local time. One man was seen to leave the boat in a wheelchair.

Officials for the United Nations refugee agency (UNHCR) and the International Organisation for Migration (IOM) reported that some of the dead were children between the ages of 10 and 12.

Prosecutor Giovanni Salvi told reporters: “Two people are currently held in custody following the testimony of survivors: the captain, of Tunisian origins, and a Syrian male national.

“The remaining 25 migrants are free. They will be identified following immediate care and are expected to request asylum.”

Salvi said the boat that sank had three levels and the doomed migrants were locked in the hull and middle deck.

The president of the Italian Red Cross, Francesco Rocca, said: “[The] migrants were very shocked, but overall in good conditions. Only three people needed particular care. One is being hospitalised.”

Another source involved in the humanitarian efforts told the Guardian: “They are very distressed. They could express themselves but most of them didn’t say much and you can’t push them too much in these circumstances … They were all young. The average age 25, I would say.”

Even as the survivors were brought to shore, further rescues were under way to help save migrants trapped on two vessels carrying about 450 people off the Libyan coast. Earlier, the IOM said “at least” 20 fatalities had been reported from one of the vessels, carrying about 300 people.

Meanwhile, a fragile wooden boat with more than 80 people aboard ran aground off the Aegean island of Rhodes. The Greek authorities reported at least three people had been killed, including a child.

At the port in Catania, Sicily, tents were set up to provide medical assistance. The Red Cross, with a team of 30 people, mostly volunteers, stayed late into the night, along with linguistic and cultural mediators who speak English, French and Arabic.

Among them was Khadija, a young volunteer originally from Morocco who started work only two months ago. “I am Muslim. It’s important to deal with people in these conditions knowing their culture and background,” she told the Guardian. The Italian minister of infrastructure and transport, Graziano Delrio, and Catania’s mayor, Enzo Bianco, also witnessed the arrival of the rescue ship.

“We can say that 800 are dead,” said Carlotta Sami, spokeswoman for the UNHCR. “There were a little over 800 people on board, including children aged between 10 and 12. There were Syrians, about 150 Eritreans, Somalians … They had left Tripoli at about 8am on Saturday.

“[The] migrants looked exhausted, fragile, astonished to see so many people waiting for them. They will need psychological support. They are receiving food and water.”

Flavio Di Giacomo, spokesperson for IOM Italy, said those on board had come from Gambia, Ivory coast, Somalia, Eritrea, Mali, Tunisia, Sierra Leone, Bangladesh and Syria. Reports said all those on board were male, several of them unaccompanied children.

Adult survivors will now be taken to a reception centre in nearby Mineo, the biggest centre of its kind in Europe, which holds up to 4,000 people. The children will be moved to a separate centre, La Madonnina in Mascalucia, also in Catania province.

Such reception areas are nearing full capacity and Italian officials on Monday warned that asylum policies in Europe needed to be amended to spread migrants more equally throughout the EU.

They will be interviewed there by a commission from the Italian ministry of the interior. Official Italian statistics says that some sort of international protection is granted to 70% of migrants.

But typically it would be several months before they know if they have been granted asylum or if their request has been rejected.

Anger has spread across Italy at what is increasingly perceived as a humanitarian tragedy to which the rest of Europe is turning its back. Italy’s prime minister, Matteo Renzi, compared the situation to the slaughter of Bosnian Muslims supposedly under international protection in Srebrenica 20 years ago.

“Twenty years ago, we and Europe closed our eyes to Srebrenica. Today it’s not possible to close our eyes again and only commemorate these events later,” an agitated Renzi said in a press conference.

In Catania, around 50 activists gathered, chanting: “Stop Fortress Europe, stop the disasters”, “European asylum for refugees”, “Emigration is not a crime” and “No borders, no nation, stop deportation”.

Marilena Bandieramonte, a university researcher in astrophysics, had brought flowers: “I’m here with 10 people among colleagues and friends. We brought flowers to remember those who didnt make it and to show solidarity with the migrants.”

Australia’s prime minister has urged European leaders to adopt tougher border control measures. Tony Abbott, whose government implemented a strict policy of turning back asylum seekers’ boats in a bid to discourage them from trying to reach Australia, called the latest Mediterranean crisis a “terrible, terrible tragedy” and suggested Europe follow Australia’s lead to ensure it was not repeated.

“The only way you can stop the deaths is to stop the people smuggling trade. The only way you can stop the deaths is, in fact, to stop the boats,” Abbott told reporters in the nation’s capital, Canberra. “That’s why it is so urgent that the countries of Europe adopt very strong policies that will end the people smuggling trade across the Mediterranean.”

The UK former Liberal Democrat leader Lord Ashdown has called for a fresh strategy to target networks of people smugglers in north Africa, including the possible use of armed force to destroy boats before they can ferry desperate migrants across the Mediterranean.

Ashdown, who served as a royal Marine before entering parliament, said: “It is unsustainable and unacceptable to have a policy of drowning refugees when we should be attacking the smugglers. We should be helping countries like Libya, Egypt and Tunisia, the departing nations, to attack people smugglers.

“There may also be a case for using special forces of interdiction to destroy the boats before they leave port.”

A summit of EU leaders is to take place in Brussels on Thursday to hammer out the details of the measures hurriedly agreed on Monday. The 28 EU governments called for much closer cooperation with Libya’s neighbours, such as Egypt, Tunisia, and Niger, in an attempt to close down the migratory routes.

But senior political figures and EU officials conceded this would be difficult and also voiced scepticism about the emphasis on targeting the traffickers.

Before Sunday’s disaster, aid agencies estimated that 20,000 migrants had reached the Italian coast this year and 900 had died.

The Italian coastguard ship Bruno Gregoracci docked in Malta at about 8am and dropped off two dozen bodies recovered from this weekend’s wreck, including children, according to the aid agency Save the Children. They will be buried on Malta.

While search-and-rescue operations continued near the site of the shipwreck, the captain of the Italian vessel Gianluigi Bove told reporters in Malta that it was unlikely any more survivors would be found.

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