European Union leaders meeting in Malta have agreed on a plan to reduce the flow of migrants from Libya.
Libya's UN-backed government will receive €200m ($215m, £171m), including funding to reinforce its coastguard.
Most of the thousands who make the dangerous crossing over the Mediterranean to Italy are from African countries.
The EU hopes Libya will be better able to disrupt people-smuggling networks and turn back migrant boats.
But human rights groups have voiced concern at the EU's strategy, and the UN-backed government in Libya has limited control over its own territory.
Hundreds of thousands of migrants try to reach Europe each year. Many of them drown while crossing the Mediterranean.
On Thursday, Italy's coastguard said more than 1,750 migrants had been rescued in the Mediterranean within 24 hours.
What does the agreement say?
In their declaration on migration, the 28 EU leaders said: "A key element of a sustainable migration policy is to ensure effective control of our external border and stem illegal flows into the EU."
The plan includes:
- Increased training and equipment for the Libyan coastguard
- Stepped up efforts to block smuggling routes
- Better conditions for migrants at Libyan reception centres
- More EU involvement with countries near Libya to slow the influx
- Supporting local communities on migration routes and in coastal areas to improve their socio-economic situation
The declaration says the EU remains committed to an earlier deal with Turkey which came into force last March and resulted in a sharp reduction of migrants travelling to northern Europe from Syria via the Balkans.
However, analysts say a similar result is unlikely in the immediate term in the central Mediterranean because of the continuing instability in Libya.
They warn that reliable partners in Libya are hard to find and that shutting existing routes might simply lead to the opening of new ones.
Why are rights groups concerned?
Some groups accuse the EU of making Libya seem safe and abandoning humanitarian values. They cite bad conditions in reception camps and continuing dangers faced by migrants.
"Libya is not a safe place and blocking people in the country or returning them to Libya makes a mockery of the EU's so-called fundamental values of human dignity and rule of law," the medical charity Medecins Sans Frontieres said.
Amnesty International tweeted that the agreement would cause "horrendous suffering".
Why are the migrants coming?
Most of those arriving in Italy from Libya come from a range of African countries, some fleeing persecution, many seeking a better life.
Migrants have fled Nigeria, for example, because of the instability in the north caused by the Islamist insurgent group Boko Haram. In Eritrea, many flee to escape military service which can last for decades and was compared in a UN report to slavery.
More than 180,000 migrants arrived in Italy last year, and more than 4,500 drowned trying to get there.
Why is Libya a problem?
Since the fall of former leader Muammar Gaddafi in 2011, Libya has lacked any effective central government and security has been in the hands of various local factions.
A UN-brokered government, headed by PM Fayez al-Seraj, has only limited control over the country and people smugglers have found it easy to operate.
Libya, thanks to its proximity to Europe and instability, has become a centre for people trafficking from Africa.
Migrants who arrive from Libya tell of violence and trauma.
A note on terminology: The BBC uses the term migrant to refer to all people on the move who have yet to complete the legal process of claiming asylum. This group includes people fleeing war-torn countries such as Syria, who are likely to be granted refugee status, as well as people who are seeking jobs and better lives, who governments are likely to rule are economic migrants.