European Union leaders faced stern warnings at a summit meeting Thursday over failed pledges to tackle the refugee emergency, as well as growing pressure to strengthen external borders and unify their asylum policies.

Away from the marbled EU headquarters in Brussels, migrants continued to risk the dangerous journey. Greece recovered seven more bodies off the island of Lesbos after a migrant boat collision, and shivering newcomers streamed into Croatia seeking aid and shelter.

More than 500,000 people fleeing war or poverty have entered Europe this year, most of them via Greece and Italy, overwhelming border authorities and reception facilities. EU leaders promised last month to provide hundreds of millions of euros for Syrian refugees and to help Africa better manage its borders, as well as funding experts to fingerprint and screen new arrivals in Italy and Greece.

European Commission President Jean-Claude Juncker said Thursday he was still waiting.

"The member states have got to do what they promised to do," he said.

"It's a question of credibility."

The European Commission complained Wednesday that only three of 28 nations have pledged a total of just 12 million euros ($13.7 million) to a fund to help African nations better manage their borders. The pot is meant to total 1.8 billion euros (about $2 billion) over two years.

The EU's border agency and asylum office have appealed for a total of around 1,000 officers to help fingerprint people and decide whether they are eligible for asylum. So far, about a dozen of the 28 EU nations have offered around 130 personnel.

"We can, and must, do much better," said EU President Donald Tusk, adding that the influx of migrants could get much worse.

"Libya is still volatile. And the situation in Syria is deteriorating. All this may lead to a new massive exodus of refugees," Tusk said. "It is our obligation to be prepared for all possible scenarios."

European Parliament President Martin Schulz asked leaders to consider urgently allocating funds for care of refugees in countries like Jordan, Lebanon and Turkey, and said EU member states were guilty of a "dereliction in duty."

Many people are calling for a common European asylum policy, though no major decisions are expected imminently.

The situation for migrants continuing to travel north remained dire.

Greece's coast guard recovered seven bodies — including those of three children and a baby — and was searching for another person missing Thursday after a wooden boat carrying migrants collided with a patrol boat and sank during a rescue operation near the eastern Aegean island of Lesbos.

The coast guard said it has rescued 830 people between Wednesday morning and Thursday morning off the eastern Aegean islands.

Many pointed to the significant role of Turkey in the crisis.

German Chancellor Angela Merkel told the German parliament before her Brussels departure that "without doubt Turkey plays a key role in this matter. Because with more than 2 million refugees it currently bears the main burden of the flight from Syria."

The EU has offered Turkey 1.8 billion euros to help deal with the refugee challenge and is looking at easing visa restrictions for Turkish citizens.

President Recep Tayyip Erdogan wants European backing for a no-fly zone and safe area in northern Syria, and for Turkey's EU membership talks to be accelerated.

Senior EU officials are currently in Turkey trying to reach an agreement on the way ahead, and Juncker said the discussions "are going in the right direction."

Meanwhile, a steady flow of people crossed from Serbia into EU member Croatia, many unprepared for the cold autumn weather and strong winds brushing across the flatland. Wrapped in grey blankets, families stood in line at a temporary admission center in Opatovac as aid workers distributed food and took mothers with babies to heated containers.

Croatian Foreign Minister Vesna Pusic, visiting the site, urged the EU leaders meeting in Brussels to boost external borders instead of putting up fences inside Europe, as neighboring Hungary has done.

"This is the turning point when Europe is deciding whether it will be marked by walls and barbed wires or whether it will be a reasonable continent of cooperation that uses political means to address the causes of such misery," she said.

Migrants are increasingly preyed on by trafficking networks.

Organized crime networks, with backgrounds in drugs, money laundering or other illicit trade, have joined the lucrative business of smuggling migrants, the Europol EU law enforcement agency said Thursday.

"They are so many that the human smugglers just open doors of cars for example, or lorries, and say 'If you don't pay me enough, go away. I have hundreds of thousands willing to be smuggled,'" said Gerald Tatzgern, head of Austria's federal unit combatting human trafficking, said at a special Interpol meeting on migrant smuggling.

While EU leaders focused on refugees fleeing war, U.N. Secretary-General Ban Ki-moon said all migrants deserve protection, help and support. Speaking to the Italian Parliament on Thursday, Ban also said all countries are obliged to shoulder the burden of welcoming migrants, not just those on the front lines like Italy and Greece.