By Gabriela Baczynska and Robert-Jan Bartunek
BRUSSELS (Reuters) - European Union ministers on Thursday raised the prospect of further tightening unilateral border controls unless there was a sharp drop in the number of migrants arriving from Turkey by the time of an EU-Turkey summit on March 7.
Seven European states have already reinstated border controls within the cherished but creaking Schengen free-travel zone, putting huge strain on Greece, which can no longer wave the tide of arrivals from Turkey onward through the Balkans.
More states said they would follow suit unless a deal promising Turkey 3 billion euros ($3.3 billion) in help to house refugees from the Syrian war in return for preventing them traveling on to Europe yielded fruit before the summit.
"By March 7, we want a significant reduction in the number of refugees at the border between Turkey and Greece," German Interior Minister Thomas de Maiziere said as he arrived at an EU justice and home affairs ministers' meeting in Brussels.
Germany has been pushing the Turkey plan hard but many other EU states are increasingly frustrated and skeptical.
More than a million refugees and migrants from the Middle East and Africa reached Europe least year, most of them coming from Turkey via Greece.
Another 110,000 have arrived on the continent this year, and the pace is set to increase as improving weather encourages more people to try the perilous trip across the Mediterranean.
"The 6th of March, the 7th of March is when you can expect the spring influx to rise ... we have until that time to find solutions that mostly involve the Greek-Turkish influx, the border there," said Klaas Dijkhoff, migration minister for the Netherlands, which now holds the EU's rotating presidency.
"If that doesn't lead to lower numbers, we'll have to find other measures and we'll have to do more contingency planning ... That's a very crucial date to see to what extent we succeed in lowering the influx towards Europe as a whole, or we have to take other measures."
The crisis was exacerbated when German Chancellor Angela Merkel last year waived EU procedures to take in hundreds of thousands of Syrians, and mutual recriminations have sabotaged efforts to share the burden systematically across the EU.
"The outlook is gloomy ... We have no policy any more. We are heading into anarchy," said Jean Asselborn, Luxembourg's foreign minister. "Our credibility is in doubt, and that is very bad for Schengen and the European Union."
Belgium, France, Germany, Norway, Sweden and Denmark have all introduced emergency border controls, allowed under the Schengen rules. But Austria, the last stop-off for most of the migrants as they head for Germany, infuriated the EU and Berlin last week by announcing daily caps on the number of people it processes.
CASCADE OF CLOSURES
The decision set off a cascade of similar moves back along the main migration route through the Western Balkans, leaving ever more migrants stuck in Greece.
"If Greece is not able or willing to secure the EU's external border, others have to act," Austrian Interior Minister Johanna Mikl-Leitner said.
The Slovak minister also said more pressure should be put on Greece to manage its borders.
Greece, struggling to emerge from years of economic crisis, for its part accused fellow EU states on Wednesday of forcing it to shoulder a burden disproportionate to its size, and Prime Minister Alexis Tsipras threatened to respond by blocking other EU decisions.
Hungary's anti-immigrant government on Wednesday announced a national referendum on whether to take in an assigned quota of migrants, as had been agreed by EU leaders last year to offer some relief to Athens.
Its foreign minister said on Thursday that the referendum would only cover future proposals as Hungary has already challenged a previous EU quota decision in court.
The Western NATO alliance has sent ships to the Aegean to provide reconnaissance on migrant flows with the aim of helping to stem people-trafficking. After late-night talks in Brussels, NATO said it had resolved differences between Greece and Turkey over the terms of the mission, and one said it could be operational before March 7.
(Additional reporting by Francesco Guarascio, Alastair Macdonald, Tom Koerkemeier in Brussels, Michele Kambas and George Georgiopoulos in Athens; Writing by Gabriela Baczynska; Editing by Kevin Liffey)