Syrian refugees react in front of a Greek police cordon while trying to reach a narrow border crossing into Macedonia near to the Greek village of Idomeni December 4, 2015 (Reuters)

An exhausted woman colapses in her efford to cross into Macedonia at the northern Greek border station of Idomeni, Greece, Friday, Dec. 4, 2015 (AP)

Migrants and refugees wait outside the registration camp near the southern Macedonian town of Gevgelija, Friday, Dec. 4, 2015 (AP)

Refugees wait at the Greek-Macedonian border to be permitted by Greek policemen to cross the border, near the northern Greek village of Idomeni, Saturday, Dec. 5, 2015 (AP)

A Syrian refugee feeds his child in front of a fence at the Greek-Macedonian border near the village of Idomeni in Greece December 5, 2015 (Reuters)

Migrants await entry into Macedonia on the Greek side of the border photographed through a fence from Macedonian side of the border, near the southern Macedonian town of Gevgelija, Saturday, Dec. 5, 2015 (AP)

Syrian refugees struggle to enter Macedonia through a narrow border crossing as Macedonian policemen try to shut a metal gate near to the Greek village of Idomeni December 4, 2015 (Reuters)

A Syrian refugee woman walks through a Greek police cordon whille trying to reach a narrow border crossing into Macedonia near to the Greek village of Idomeni December 4, 2015 (Reuters)

A Pakistani migrant, who has been stranded at Idomeni for five days, warms himself over a makeshift fire in front of the wire fence that separates the Greek side from the Macedonian one at the northern Greek border station of Idomeni, Saturday, Dec. 5, 2015 (AP)

A woman covered with a blanket walks in front of Greek police forces on her way to the Greek- Macedonian border gate at the northern Greek border station of Idomeni, Saturday, Dec. 5, 2015 (AP)

Refugees wait to be allowed to cross into Macedonia at the northern Greek border station of Idomeni, Saturday, Dec. 5, 2015 (AP)

Syrian refugees struggle to enter Macedonia through a narrow border crossing as Macedonian policemen try to shut a metal gate near to the Greek village of Idomeni December 4, 2015 (Reuters)

A Syrian refugee woman holding her baby reacts in front of a Greek police cordon while trying to reach a narrow border crossing into Macedonia near to the Greek village of Idomeni December 4, 2015 (Reuters)