The Tunisian captain of a boat that capsized off Libya on Sunday, killing hundreds of migrants, has been charged with reckless multiple homicide, Italian officials say.

He has also been charged along with a member of the crew with favouring illegal immigration.

The two were among 27 survivors who arrived in Sicily late on Monday.

The charges come after the EU set out a package of measures to try to ease the migrant crisis in the Mediterranean.

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

A homicide investigation has been opened into the disaster.

After speaking to the survivors, the UN refugee agency said that about 800 people had died in Sunday's disaster. Earlier accounts had put the death toll at about 700.

"There were a little over 800 people on board, including children aged between 10 and 12," said Carlotta Sami, of the United Nations High Commissioner for Refugees in Italy.

"There were Syrians, about 150 Eritreans, Somalians... They had left Tripoli at about 8am on Saturday."

At the scene: James Reynolds, Rome correspondent

The survivors stood still on the rescue boat. They looked exhausted. One shook hands with the mayor of Catania and put his hand to his chest in a gesture of thanks.

Francesco Rocca runs the Italian Red Cross: "They are under shock, completely shocked. They repeat their phrases about the fact that they are the only survivors on the tragedy.

"Some of them want to speak, some of them want to stay silent. You can imagine they are under a lot of pressure. It's the first time I see such a high level of shock. It's clear from their eyes."

Two survivors told rescue workers that they had managed to stay afloat by clinging to the bodies of their fellow passengers. Others said that the children on board drowned because they were trapped on the boat's lower two levels.

Grey line

Mr Salvi said hundreds of passengers had been locked below deck and hundreds more were crammed on to its upper deck.

It is believed the boat capsized when an attempted rescue by a Portuguese merchant ship caused panic. Only 28 people were rescued.

'Sense of solidarity'

Earlier, EU foreign policy chief Federica Mogherini said the 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.

Earlier, 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 Sunday's 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.