The European Commission has said it will allow border checks in the Schengen area for six more months. More than 1 million migrants entered the EU in 2015, most from war-torn countries in the Middle East and Africa.
The European Commission agreed to extend select internal border controls for six months, citing a lack of effective external controls by Greece.
A hallmark of European Union integration, the Schengen zone normally allows passport-free travel across 26 countries from Portugal to Estonia.
European Commission Vice President Frans Timmermans defended the move on Wednesday.
"There is still considerable migratory pressure at our external border, and large numbers of migrants present in Greece," Timmermans said. "Therefore, as long as serious deficiencies in [Greece's] border management persist some internal border control measures should be maintained."
The extended border controls will remain for the German-Austrian border, as well as Austria's southeastern flank with Hungary and Slovenia. Farther north, the border controls will remain for people entering Denmark from Sweden or Norway.
Internal border controls can be imposed for up to two years in emergency situations, but EU Migration Commissioner Dimitris Avramopoulos vowed that the internal controls would be eliminated before the year is out.
"The aim is that, by the end of this year, the Schengen zone will be fully normalized," Avramopoulos told journalist in Brussels.
Some EU members began erecting border controls last year as more than 1 million migrants - the vast majority of them war refugees from Syria, Iraq and Afghanistan - arrived in Europe seeking safety.
Fewer asylum-seekers from Turkey
Migrants flows from Turkey to Greece have dropped dramatically since the EU reached a controversial agreement with Turkey in March.
The Commission, however, said "the sustainability of the sharp drop in numbers seen over the last weeks still needs to be confirmed."
The European Commission attributes the reduced flow to "significant progress" by Greece in addressing the various problems but not all have been fixed yet. There is still "a risk of significant secondary movements" by migrants within Europe, it warned.
There is growing concern is that desperate migrants will try to make their way into the EU via perilous Mediterranean crossings to Italy.
Austria is already constructing an Alpine border control along is border with Italy. The Brenner Pass is a high-volume crossing point for commercial goods.
Avramopoulos side-stepped questions on the issue, but said that the two countries are trying to negotiate a solution.
Border controls are anathema to the free flow of goods, inflating transportation times and, critics have said, ultimately raising retail prices.
The array of ongoing, and emerging, border controls have also sparked fears that border-free travel across Europe is in jeopardy - hence Avramopoulos' efforts to allay such fears.
bk/sms (dpa, Reuters, AFP)