Refugees sleep next to the fence at the Greek-Macedonian border near Idomeni on February 28, 2016.
Some 6,500 people were stuck at the Idomeni camp on Greece's northern border with Macedonia on February 27 (AFP)

Migrants and refugees queue for some food at an overcrowded refugee camp at the Greek-Macedonian border near Idomeni on February 28, 2016. (AFP)

Rescue swimmer Duncan Barrow of Norfolk, UK, aboard a rescue speedboat of MOAS, Migrant Offshore Aid Station, a Malta- Feb. 28, 2016. (AP)

Migrants and refugees make their way through a field towards the Greek-Macedonian border February 28, 2016, as thousands of people wait to cross the border near the Greek village of Idomeni. (Reuters)

Children sleep as refugees queue for some food at an overcrowded refugee camp at the Greek-Macedonian border near Idomeni on February 28, 2016. (AFP)

A refugee holding his baby warms by a fire at an overcrowded camp at the Greek-Macedonian border near Idomeni on February 28 , 2016. (AFP)

A seagull flies over life jackets that were abandoned after they were used by migrants to reach the eastern Greek Island of Agathonisi on the Aegean Sea, from the nearby Turkish shores, Sunday, Feb. 28, 2016 (AP)

A woman holds her baby after sleeping outside in a field at an overcrowded camp at the Greek-Macedonian border near Idomeni on February 28 , 2016. (AFP)

Stranded Refugees from Syria are covered with blankets while waiting to be allowed to cross the Greek-Macedonian border near the northern Greek village of Idomeni, Sunday, Feb. 28, 2016 (AP )