By Foo Yun Chee and Gabriela Baczynska
The European Union executive says Greece has made progress in policing its part of the bloc's external border, but that more action is needed before emergency controls inside the free-travel zone can be lifted.
Germany and other EU states introduced temporary border checks inside the so-called Schengen area, blaming Athens for failing to control its frontiers amid a mass influx of migrants and refugees arriving on Greek Aegean islands from Turkey.
The European Commission must decide by May 12 whether to extend those border checks.
Until recently, most migrants were being waved through on their journey to wealthy northern Europe, often without being registered as the arrival of more than a million people over the last year, mainly through Greece, overwhelmed the country.
A cascade of border closures since late last year has cut the flow of people through the Western Balkans, the main migratory route from Greece to Germany, to a trickle.
Arrivals from Turkey have also slowed since a controversial deal was agreed with the EU last month under which Ankara will take back all migrants and refugees, including Syrians, who enter Greece through irregular routes.
While this has taken some immediate pressure off Greece, Germany and Sweden have made clear that they think it is too early to lift the border checks. The Commission has said it wants to restore the normal functioning of the Schengen zone of passport-free travel by the end of the year.
The EU executive said on Tuesday that Greece had made "significant progress" on the border but that "further improvements" were needed, including more rapid use of EU funds provided to help the country manage the flow of people.
Should Brussels decide Greece is not controlling its borders well enough, it could allow for the extension of border checks for up to two years.
That would be a major political blow for the 28-nation bloc, as freedom of movement is one of the most tangible results of European integration for the EU's 500 million citizens.
Brussels has disbursed €181 million in emergency assistance to Athens and relief groups working on the migration crisis there since the start of 2015, the Commission said, on top of long-term funding for Greece envisaged at €509.5 million euros over 2014-2020.