Southern European leaders called Friday for a fair distribution of migrants arriving from across the Mediterranean as the latest NGO boat carrying rescued families was denied a safe port by Italy.
The leaders of Cyprus, France, Greece, Italy, Malta, Portugal and Spain said the European Union should "guarantee effective implementation of the principle of solidarity and fair burden-sharing between member states."
A joint declaration at the end of the summit in Valletta also said "efforts to break the smugglers' business model need to be further enhanced, with the aim to also prevent tragic loss of life."
The wording appeared to target the boats of non-governmental organisations that rescue migrants from the Mediterranean, but which are accused by far-right politicians such as Italy's Interior Minister Matteo Salvini of encouraging human trafficking.
Italian Prime Minister Giuseppe Conte at the summit voiced "frustration" that the EU "talks about solidarity without applying it".
The German-operated Sea Watch 3 NGO rescue vessel is currently off Italy's southern Lampedusa island with 53 migrants on board who were rescued off the coast of Libya and since denied entry to Italian ports.
Mr Salvini says that the rescue boats prevent the Libyan coastguard from picking up the migrants and returning them to Libya.
"All vessels operating in the Mediterranean must respect the applicable international laws and not obstruct operations of the Libyan Coastguard," the summit statement said.
Mr Salvini, who is also deputy prime minister and leads the powerful right-wing League party in the coalition, has issued a decree ordering law enforcement authorities to take all necessary measures to prevent the entry into or transit through Italian waters of such ships.
Mr Salvini has seen his popularity soar in the last year with a hard line against migrants which has included closing ports to rescue vessels.
Sea Watch International on Friday tweeted that its vessel was "still waiting for a port of safety 16 miles off Lampedusa", calling for people to sign a petition for the migrants to be taken in by German cities.
Mr Salvini said the vessel was now "wandering around the Mediterranean forcing women, men and children into unnecessary suffering."
Italy and Malta, the closest countries to North Africa, said ahead of the summit that more should be done to stop migrants leaving, including by bolstering the training and resources of the Libyan coastguard.
Rome and Valletta insist on there being a fair distribution of migrants to other EU countries, while countries such as France say migrants should disembark at the closest port and then be voluntarily redistributed around Europe.
More than 12,000 people have died since 2014 trying to flee Libya to Europe by what the UN refugee agency calls the "world's deadliest sea crossing".
The seven nations meeting in Malta on Friday represent close to 40 percent of the EU's population and gross domestic product and half of its coastline, Malta said.