Mediterranean migrants tragedy
Surviving immigrants lie on the deck of Italian coastguard ship Bruno Gregoretti in Senglea, in Valletta's Grand HarbourReuters

Italian authorities have arrested the Tunisian captain and a Syrian crew member of the 19 April migrant boat disaster on suspicion of people trafficking after the men arrived in the Sicilian port of Catania.

The pair have been charged with people trafficking and reckless multiple homicide in relation to the disaster.

Italian police interviewed 27 survivors of the wreck as they were brought to Italy on a coast guard vessel. As many as 900 people are believed to have drowned.

Search and rescue operations will be stepped up and there will be a campaign to destroy traffickers' boats.

Italian Infrastructure Minister Graziano Delrio said Catania state prosecutor Giovanni Salvi, who has opened a homicide investigation into the disaster, ordered the arrest of the two. Officials from the prosecutor's office said they were the captain of the vessel and his first mate.

"Prosecutor Salvi has made two arrests this evening of persons involved, that shows the Italian justice is working," Delrio told reporters at the port.

A homicide investigation has been opened into the disaster, he added.

Speaking about Sunday's disaster, in which only 28 of an estimated 900 migrants were rescued, Salvi said hundreds had been locked below deck when the boat capsized.

He said more passengers were locked inside cabins on another deck and hundreds more were crammed on to its upper deck.

EU measures to combat illegal trafficking of migrants:

An increase in the financial resources of Frontex, which runs the EU's Mediterranean rescue service Triton, and an extension of Triton's operational area.

Joint processing of asylum applications - within two months of their being lodged

Fingerprinting and recording of all migrants

An EU pilot project on migrant resettlement - this would be voluntary

Offer of return travel packages

Immigration liaison officers in key countries

Earlier, EU foreign policy chief Federica Mogherini said a 10-point package set out at talks in Luxembourg was a "strong reaction from the EU to the tragedies" and "shows a new sense of urgency and political will".

"We are developing a truly European sense of solidarity in fighting human trafficking - finally so."

The measures include an increase in the financial resources of Frontex, which runs the EU's Mediterranean rescue service Triton, and an extension of Triton's operational area.

The EU had been criticised over the scope of Triton, which replaced the larger Italian operation Mare Nostrum at the end of last year.

As the talks took place late on Monday, Italy and Malta said at least two other rescues were taking place.

Italian Prime Minister Matteo Renzi said one of the vessels was a dinghy off the Libyan coast with about 100-150 people on board. The other was a larger boat carrying 300 people.

Also, the Greek coastguard said a vessel carrying dozens of migrants had run aground off the island of Rhodes. Three people had died and 80 were rescued, it said.

Maltese Prime Minister Joseph Muscat said the disaster off Libya was "a game changer", adding: "If Europe doesn't work together history will judge it very badly."

Continued political instability in Libya has allowed human trafficking there to flourish.

Ms Mogherini said they had discussed the possibility of supporting a government of national unity in Libya.