By Gabriela Baczynska and Tom Körkemeier
AMSTERDAM (Reuters) - European Union interior ministers on Monday urged Greece to do more to control the influx of migrants, some threatening to exclude it from the continent's prized passport-free travel zone as the crisis increasingly divides the bloc's members.
Greece was the main gateway to Europe for more than a million refugees and migrants who reached the EU last year. But it has been criticized for a failure to control the flow of arrivals, which have shown little sign of falling over the winter months.
The EU has taken various steps to give cash-strapped Athens financial assistance to deal with the crisis, but many member states believe Athens is not using that enough. Of five registration "hot spot" centers that were due to be set up for migrants arriving in Greece, only one is running so far.
Overwhelmed by the influx, Greek law enforcement officials have often let migrants through deeper into Europe rather than keep them on Greek soil for proper registration - the first necessary step agreed by the EU before people can move further.
Athens says the numbers are impossible to manage and blames the other 27 EU states for not offering real help. The crisis has put the passport-free Schengen zone - hailed by top EU officials as the greatest achievement of European integration - on the verge of collapse.
"If we cannot protect the external EU border, the Greek-Turkish border, then the Schengen external border will move toward central Europe," said Austria's Interior Minister Interior Minister Johanna Mikl-Leitner.
"Greece must increase its resources as soon as possible and accept help," she said on arriving at informal interior minister talks in Amsterdam.
The Schengen zone comprises 26 states, most of which are also EU members. Germany, France, Austria and Sweden are among several countries that have introduced temporary border checks as they struggle to control the flow of people.
"Speaking about timetables, it's already too late. We have seven countries with border controls," Sweden's interior minister Anders Ygeman told Reuters.
He said migrant registration centers need to start functioning in Greece and Italy as planned.
"In the end, if a country doesn't live up to its obligations, we will have to restrict its connections to the Schengen area. If you don't have control of your borders, it will have consequences for the free movement."
Excluding Greece would require applying Article 26 of the Schengen code. Germany, the main destination for refugees and migrants fleeing war and poverty in the Middle East and Africa, first floated the idea last year.
The Greek minister did not speak on arrival but the EU Migration Commissioner Dimitris Avramopoulos, himself Greek, sought to talk down the risk of excluding the country from Schengen.
"Nothing like this has been proposed or discussed. What we have to do is to better manage our external borders. It's obvious that frontline member states must work more and here we are...to help them to better do their job," he said.
The Luxembourg interior minister was also against leaving Greece outside Schengen, while Germany's Thomas de Maiziere said that he wanted to preserve Schengen but that time was running out.
Berlin hopes a deal agreed with Turkey last November would mean fewer migrants arrive in Greece, but the deal has so far had limited impact.
Top EU officials have echoed Berlin's warnings recently that Schengen will not survive without a dramatic change in the coming weeks in the way the bloc handles the crisis.
However, EU countries, worried about growing anti-migrant sentiment at home, have failed to agree.
As the ministers arrived by canal for talks at Amsterdam's maritime museum, they passed a protest by Amnesty International, a boat packed with mannequins in bright life vests designed to resemble migrants arriving in Europe.
"Leaders of Europe, it's not the polls you should worry about," a sign said. "It's the history books."
(Writing by Gabriela Baczynska; Editing by Philip Blenkinsop and Hugh Lawson)