Greek authorities confirmed Monday that they ordered special police units to clear the informal refugee camp at Idomeni, on the country's border with Macedonia.
It was not immediately clear how the action would be carried out, but officials indicated that they are reluctant to use force.
"We will certainly not gallop into the camp or carry any sort of a cleansing operation," the spokesman for the national refugee crisis body, Giorgos Kurytsis, told dpa in Athens. The process is to last several days, he added.
The European Union backed the plan, voicing hope that there won't be any violence.
"The commission repeatedly has expressed the view that these people should be moved from their makeshift camp to more organized reception facilities," European Commission spokesman Margaritis Schinas told reporters in Brussels.
"The Commission welcomes any initiative taken by Greek authorities to evacuate Idomeni and move the migrants currently present in the camp to organized reception facilities," he said.
Greece built the camp at Idomeni at the peak of the migration crisis in 2015 for a brief stay of up to 2,000 people during their wait to cross the border and continue their trip north through Macedonia and the Balkans en route to rich EU countries.
But as Balkan countries began restricting the flow of migrants, including refugees from Syria, the crowd snowballed to around 12,000 in March, when the border was totally shut.
Migrants at Idomeni refused to leave, hoping they will be allowed to continue.
Greece meanwhile established several camps for the people at Idomeni, but few of them took the offer to relocate.
Skirmishes with police and violent breaks through the border fence have occurred repeatedly since then, and Greek authorities were concerned that an effort to clear the camp may stir up trouble again.
Athens is under pressure to take the step, however, as people stranded at Idomeni are blocking the railroad passing there, causing damage to businesses on both sides of the border.