The governor of Greece's Central Macedonia province has said he would like to declare a state of emergency over the thousands of migrants stranded in the region by closed borders.
"Here [at the Idomeni border crossing] we have 13,000 people and further south another 5,000 migrants in refugee camps," Apostolos Tzitzikostas told Greek broadcaster Skai from Idomeni on the border with the former Yugoslav republic of Macedonia.
Greece's northern neighbour closed its borders to the wave of migrants and is only allowing a few people to pass through its territory each day.
The Greek government estimates that 32,000 migrants have been stranded in Greece after Balkan countries closed their borders, stopping them from proceeding along the so-called Balkan route to richer countries in northern and western Europe.
On Saturday, EU Migration Commissioner Dimitris Avramopoulos said Greece could end up hosting more than 100,000 migrants by the end of March.
Heavy morning rains turned the makeshift camp at Idomeni into a mud bath, while temperatures were just 4 degrees Celsius. Hundreds were suffering from the cold and were experiencing breathing problems. The hygienic situation was quite serious.
Doctors and sanitation workers will be deployed immediately to the Idomeni camp, Greece's crisis management committee said Saturday. Athens announced the creation of committee on Thursday to coordinate efforts surrounding migrant accommodation and humanitarian aid.
The UN's refugee agency UNHCR said earlier in the week that a humanitarian crisis was developing in Greece.
Aid organizations are advising the migrants that there is better accommodation in reception camps to the south of the border, such as Nea Kavala, some 15 kilometres from Idomeni.
Most migrants are not taking this advice and are remaining by the border crossing, hoping that the Macedonian authorities will open the border fence if only briefly to allow some to pass, reporters on the ground said.
A further 975 migrants arrived in the Greek port of Piraeus from the Aegean islands of Lesbos and Chios on Saturday morning, the Greek Coastguard reported.
Another 54 migrants were expected to arrive from the island of Kos later in the afternoon.
Greek Prime Minister Alexis Tsipras and the leaders of the largest Greek parties demanded Friday evening that Tsipras be invited to Monday's EU-Turkey summit in Brussels which will deal with the refugee crisis.
Tsipras would like to see the formation of a European Coastguard to be based in Greece.
He would also like to see previously agreed measures implemented, such as speedier returns of failed asylum seekers and the redistribution of migrants among all EU member states, with penalties for those that do not fulfill their obligations.