Brussels: European Union officials added last-minute tweaks to a pact with Turkey to halt the flow of migrants into Europe in an effort to make it legally watertight, but a standoff with Cyprus could yet scupper any deal at a summit this week.
Under a tentative agreement reached last week, Ankara would take back all migrants and refugees who enter the EU from its shores or are detained in its territorial waters, in return for more money, faster visa-free travel for Turks and a speeding up of its slow-moving EU membership negotiations.
For its part, the EU would admit one legal Syrian refugee directly from Turkey for each one trying to reach Europe by boat and taken back by Turkey from the Greek islands in a step meant to wreck the business model of people smugglers.
"We are certainly not giving Turkey a free ride," European Commission Vice President Frans Timmermans said. Ankara would have to enact a raft of measures within six weeks if Turks were to get visa-free travel to the 26-nation Schengen area in June.
German Chancellor Angela Merkel is pushing hardest for the deal after suffering heavy losses in regional elections on Sunday due to public anger over an uncontrolled influx of more than 1 million migrants into Germany last year.
Merkel told parliament in Berlin on the eve of the Brussels summit that no one should be "deceived" by a relative lull in arrivals since Austria and Balkan countries shut their borders.
More than 43,000 migrants and refugees are bottled up in squalid conditions in Greece after Macedonia closed its border, and more are arriving daily despite NATO's Aegean sea patrols.
"The current easing that Germany and some other member states are experiencing is one thing. The situation in Greece is the other, and it must be a big concern to us all because it is not without consequences for us all in Europe," Merkel said.
An agreement with Turkey would need to be followed by a deal among EU countries to accept quotas of refugees, she said, something several central European states have so far rejected.
European Council President Donald Tusk, who will chair the summit on Thursday and Friday, has drafted a set of principles to overcome legal and political objections to the deal, including an assurance against blanket mass returns of migrants.
"This will be a temporary and extraordinary measure which is necessary to end the human suffering and restore public order," a draft document seen by Reuters said.
Migrants arriving on Greek islands would be duly registered and entitled to apply for asylum in Greece, it said, and their applications would be processed in accordance with EU rules.
People returned to Turkey would be protected in line with international standards for refugees, even though Ankara applies the Geneva Convention formally only to people fleeing Europe.
However, Cyprus has made clear it is ready to veto any widening of EU accession talks with Turkey unless Ankara meets obligations to recognise its statehood by opening its ports and airports to Cypriot traffic. Cyprus and Turkey have been at loggerheads since a 1974 Turkish invasion of the island.
Cyprus could also try to block visa liberalisation for Turks since the EU conditions include the principle of equal treatment of all member states. Nicosia does not have a veto on the visa issue, but it could find allies among reluctant countries such as France, Spain and Austria.
EU officials declined to say whether Tusk, a former Polish premier, secured any Turkish commitment on the Cyprus issue in talks in Ankara on Tuesday, but a Turkish minister warned the EU on Wednesday against letting Nicosia hold the bloc to ransom.
"When a step has been taken towards a solution, when agreement has been reached on a package, the whole structure should not be allowed to be ruined just because of the ... caprice of one EU member country," Volkan Bozkir, minister for EU affairs, said in an NTV interview.
The EU leaders are due to meet Turkish Prime Minister Ahmet Davutoglu on Friday morning to finalise the deal.
But European Parliament President Martin Schulz, reflecting the feelings of many lawmakers deeply uneasy about Turkey's human rights record, told Germany's Funke media group he did not expect a "final breakthrough" this week.