European Union leaders on Monday pressed Turkey to take back thousands of migrants and prevent others from setting off for Europe as thousands of desperate people sat stranded in Greece.

Turkey — a temporary home to an estimated 2.75 million refugees, many from the conflict in Syria — is an indispensable EU partner in trying to dissuade people fleeing conflict or poverty from taking to makeshift boats and making the short but often-dangerous trip across the Aegean Sea.

"To avoid that refugees arrive in Greece we have to cooperate with Turkey," French President Francois Hollande said as he arrived for the EU-Turkey summit in Brussels.

In a draft statement prepared for the talks, seen by The Associated Press, the leaders said they will pursue "comprehensive, large scale and fast-track returns to Turkey of all irregular migrants not in need of international protection."

Macedonia, on Greece's northern border, has effectively sealed off the main route into the Balkans, allowing just a trickle of people through. The move — backed by Austria, Croatia, Slovenia and Hungary — has ratcheted up pressure on Greece from the other side as it simply doesn't have enough shelter for them.

Hundreds of thousands of people have used the route in recent months to try to reach preferred destinations like Germany or the countries of Scandinavia.

Before the summit, an estimated 13,000-14,000 people waited at Greece's border with Macedonia hoping desperately to be allowed to cross.

"Whatever it takes. We will go. We have nothing to go back to. Our homes are destroyed," said Lasgeen Hassan, who, with the rest of his Kurdish Syrian family, wants to reunite with relatives in Germany.

Greece's prime minister, arriving for early talks with Turkish counterpart Ahmet Davutoglu, urged his EU partners to put long-agreed and long-delayed migrant plans into action.

"Rules are for all, and everybody has to implement our common decisions," Greek Prime Minister Alexis Tsipras told reporters. "If there are agreements that are not implemented, there are no agreements at all."

EU leaders agreed in September to share 160,000 refugees arriving in Greece and Italy over two years. As of March 3, fewer than 700 people had been relocated to other European countries.

Davutoglu said he hopes the summit would mark a turning point in EU-Turkey ties. He said the meeting is as focused on Turkey's future EU membership as on the refugee emergency.

"Turkey is ready to work with the EU, and Turkey is ready to be a member of the EU as well," Davutoglu told reporters, expressing hope that the talks "will be a success story and a turning point in our relations."

The EU is desperate to halt the flow of migrants crossing the Aegean Sea. It has offered Turkey 3 billion euros ($3.3 billion) in refugee aid, fast-track EU membership and an easing of visa rules to win its support.

Dutch Prime Minister Mark Rutte, whose country holds the EU's rotating presidency, said Turkey will need extra help if more migrants are sent back.

"We will need to bring relief to Turkey, and that means you have to be willing to take people in from Turkey" who are the most likely to qualify for asylum, he said.

Human rights group Amnesty International hit out at the leaders for using Turkey as a buffer to stop migrants, calling the move "a dangerous and deliberate ploy to shirk their responsibilities to people fleeing war and persecution."

"Europe has an absolute duty to protect refugees and must make the bold decision to fast-track significant, unconditional resettlement as a matter of urgency," said the group's deputy director for Europe and Central Asia, Gauri van Gulik.

Ankara did little to allay concern about its rights record before the summit, when police on Friday stormed the headquarters of the Zaman opposition newspaper to enforce a court decision to place it and its sister outlets under the management of trustees. The step sparked two days of protests which police dispersed using tear gas and water cannons.

"Cooperation with Turkey does not mean that we have to accept anything," Hollande said. "The press must be free everywhere, including in Turkey."

Inside EU headquarters, German Chancellor Angela Merkel lobbied her partners to ensure that no mention was made of officially closing the Balkan migrant route in the final summit statement. But she faced strong opposition from Austria and several Eastern European nations.

Austrian Chancellor Werner Feymann said: "I'm all for having clearer language, for us all to say: 'We will close all routes, the Balkan route as well.' The traffickers should be given no chance."

But Merkel insisted that the answer lies not in "closing something, but about finding a sustainable solution together with Turkey."

In Athens, police patrolled a central city square to prevent migrants setting up camp after the site was cleared over the weekend.

Hundreds of people, mostly from Afghanistan, had been sleeping rough at Victoria Square after Austria and Balkans countries further north imposed border restrictions and closures.

About 34,000 migrants are currently stranded in Greece. According to the United Nations refugee agency, 2,480 people arrived on Sunday.