(ANSA-AP) - BRUSSELS - The European Union's top migration official on Thursday said efforts to manage the refugee emergency are failing as more countries tighten border security, a trend he says could unravel unity in the bloc.

"The situation is getting worse," Migration Commissioner Dimitris Avramopoulos told EU lawmakers in Brussels, noting that up to 4,000 people were arriving daily in Greece over Christmas and New Year fleeing conflict or poverty.

More than a million people landed on Europe's shores last year, many from conflict zones including Syria, Iraq and Afghanistan. Most traveled through Turkey and disembarked on Greek islands just a short - but dangerous - hop across the Aegean Sea.

Overwhelmed authorities in Greece have been unable, and in some cases unwilling, to register or lodge the migrants and hundreds of thousands of people have headed north hoping to be accepted in countries like Germany or Sweden.

Avramopoulos said that "more and more member states are reintroducing border controls" in response, including Germany, Sweden, Denmark and Austria. (ANSA).