EU leaders are due to hold an emergency summit on ways to stem the number of migrants risking the perilous journey across the Mediterranean.

BBC Europe editor Katya Adler says draft proposals include a push for a military mandate to destroy boats used by people traffickers.

More than 800 people drowned off Libya's coast on Sunday, bringing the number of deaths this year to 1,750.

Italian PM Matteo Renzi has called for direct action against people smugglers.

He described them as "the slave traders of the 21st Century".

A draft statement for Thursday's meeting in Brussels, seen by AFP news agency, says leaders will commit to "undertake systematic efforts to identify, capture and destroy vessels before they are used by traffickers".

It says EU foreign policy chief Federica Mogherini "is invited to immediately begin preparations for a possible security and defence policy operation to this effect, in accordance with international law".

Our correspondent says other plans include supporting UN efforts to help form a stable government in Libya.

Italy says 90% of the migrant boats ending up on its shores set off from Libya.

EU leaders are also expected to discuss what to do with those migrants who reach Europe. A proposal for them to be spread out more equally among all EU states is a hugely divisive issue, our correspondent adds.

On Monday, the EU set out a 10-point action plan to prevent more deaths. They include an increase in the financial resources of Frontex, the border agency 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 last year.

Some EU members had said Mare Nostrum was too expensive and expressed concerns that it was encouraging more migrants.

But human rights group Amnesty International said the decision to end Mare Nostrum had "contributed to a dramatic increase in migrant and refugee deaths".

Speaking in Washington on Wednesday, UN High Commissioner for Refugees Antonio Guterres said a co-ordinated response was needed to save lives.

"Our ability to save lives at sea has to be guaranteed, because the current situation is a tremendous tragedy," he said.

"Today we know that the fact that there is no effective rescue operation in place, has not reduced but rather increased the number of people who try to cross the Mediterranean."

He added: "There are people traffickers. And we have to take a very tough line with these people who violate human rights."

The number of people fleeing war and poverty in the Middle East and Africa has spiked in recent months, leading to huge numbers of people trying to reach Europe in unseaworthy and often overcrowded vessels.

The International Organisation for Migration says there have been 30 times as many deaths so far in 2015 as in the same period last year and the figure could rise to 30,000.

More than 500 people rescued from several other boats were brought ashore by Italian coastguards on Wednesday.