Greece is preparing to help as many as 150,000 stranded migrants as international pressure on Balkan countries led to Macedonia briefly opening its border for just a few hundred refugees.
"In my opinion, we have to consider the border closed," Greek Migration Minister Ioannis Mouzalas said.
"And for as long as the border crossing is closed, and until the European relocation and resettlement system is up and running, these people will stay in our country for some time."
At the moment, about 30,000 refugees and other migrants are stranded in Greece, with 10,000 at the Idomeni border crossing to Macedonia.
On Wednesday, hundreds of more people continued to arrive at two official camps by the border that are so full that thousands have set up tents in surrounding fields.
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Greek police helped one man who fainted after being turned back by Macedonian authorities. Others waited stoically for rain covers, or food and other essentials in chilling temperatures, some expressing frustration with bureaucratic errors by Greek officials.
Nikos Kotzias, the foreign minister, said the country could handle a capacity of up to 150,000.
"No one in Europe predicted this problem would reach such a giant scale," Kotzias told private Skai television.
"But this is not a cause for panic. The problems must be addressed soberly."
Macedonia intermittently opened the border on Wednesday, letting hundreds of people in, as European Council President Donald Tusk arrived in the country as part of a tour of the region for talks on the migration crisis.
Tusk, who is due to travel to Greece and Turkey on Thursday, hopes to ease tension among European Union leaders before they hold a summit on migration on Monday with Turkey.
European Union Humanitarian Aid Commissioner Christos Stylianides says he wants to swiftly push through a proposal to earmark 700 million euros ($A1 billion) in aid for the refugee crisis, with 300 million euros paid out in 2016.
Officials stress the program will not divert money from the EU's 1.1 billion-euro annual budget devoted to helping the world's poorest.
They note that relieving the suffering of refugees closer to their homes is a key part of the 28-nation bloc's strategy to discourage people from making dangerous journeys to Europe.
