PARIS —Turkey offered a path Tuesday to ease Europe’s migrant crisis with a two-way deal: agreeing to accept the mass return of people who struggled to reach European shores, but demanding that Europe take Syrian refugees from camps and other sites in Turkey.
The tentative pact, reached in Brussels after hard bargaining from Turkey, marks a major shift in policies among European nations that last year opened their borders to the huge flow of migrants but now have blocked their way.
For Turkey, meanwhile, the desperation in Europe gives them rare leverage to try to clear out huge refugee camps for some of the more than 2.7 million Syrians who have fled the six-year conflict. Turkey also used the summit to pry more aid money from the Europe Union and press its bid for membership in the bloc.
Under the deal, all newly arrived economic migrants and Syrian refugees who arrived in Greece by boat would be sent back to Turkey. But for each Syrian among those sent back, the European Union would be required to accept a different Syrian refugee in a “one-for-one” exchange.
An E.U. official said the deal would not affect the hundreds of thousands already in Europe whose applications for asylum have yet to be processed.
Details are still under discussion, but that would mean Syrians being moved from the Turkish camps or even refugees facing a dizzying passage: reaching Europe — usually aided by smuggling networks — then being sent back to Turkey and finally being allowed back into the European Union at some point.
The agreement also seeks to send to reinforce the last week’s message to migrants from the European Council President Donald Tusk: “Don’t come.”
Rights groups and others immediately raised questions over the pact, including whether it violated international norms that call for asylum claims to be heard before possible deportation.
Pressure was high for an accord with migrants stranded at blocked borders, crowded into makeshift encampments in Greece and thousands more arriving over the Aegean Sea. Since last year, more than 1 million migrants, asylum seekers and others have poured into Europe from places including war-ravaged Syria and Iraq.
At its most abstract, the agreement was a means of curbing the “irregular migration” that so many European leaders wish to curb. In a statement, E.U. leaders said that these “bold moves” would crack down on people smugglers and protect the continent’s external borders.
“We need to break the link between getting in a boat and getting settlement in Europe,” they said.
At a more practical level, however, the deal leaves many logistical and legal questions.
In theory, its open-ended language could require the European Union to resettle tens of thousands — and even hundreds of thousands — down the line.
Resettlement on such a potentially large scale would also depend on the participation of member states across the 28-nation European Union. But such consensus is hardly guaranteed.
Some E.U. states have strongly object to the mandatory quota proposal some diplomats implied would have to accompany the new policy. In response, Hungary’s Prime Minister Viktor Orban threatened a veto.
Legally, the deal also risks subverting traditional asylum procedures, which require that any application made must be considered and that applicants cannot be sent to countries without adequate protection.
Critics insist that Turkey falls short of offering a haven while asylum and refugee claims are sorted out.
Although Turkey ratified the 1951 Refugee Convention, it recognizes refugee status only for citizens of certain countries. Only Syrians among the current crop of refugees can currently claim such status, leaving others who have fled conflict zones such as Eritrea, Iraq, and Afghanistan without any protection.
“We know, we’ve documented, that Turkey is not a safe place for asylum seekers and refugees,” said Gauri van Gulik, Amnesty International’s deputy Europe director. “We’ve documented people being sent all the way to the south of Turkey, held in incommunicado detention, and sent back to Syria.”
The U.N. refugee agency also expressed concern about a possible “blanket returns” of refugees from the European Union — a possible violation of international law.
The agency’s Europe bureau director, Vincent Cochetel, told reporters in Geneva that it was misleading to emphasize “irregular migrants” because 91 percent of those arriving in Greece are from war-torn countries like Iraq, Syria and Afghanistan.
For Turkey, the summit ultimately provided a chance to exert considerable leverage on a decades-long push for E.U. membership as well as expedited visas for Turks seeking to live and work in Europe.
Just days after the government of Recep Erdogan seized control of Zaman, the country's largest newspaper, E.U. leaders seemed willing to look the other way in order to broker a deal.
The EU statement mentioned only that European leaders discussed “the situation of the media in Turkey," but offered no further details.
E.U. leaders plan to meet again March 18 to discuss the agreement's terms.
German Chancellor Angela Merkel said the deal represents "a breakthrough if it is to be realized, if it is to be implemented."