Large groups of migrants sat behind wired fences on the Belarusian side of the border with Poland as a tense migration standoff between Warsaw, Minsk and the European Union continued.
The European Union has accused Belarus President Alexander Lukashenko of using the migrants as pawns in a "hybrid attack" against the bloc in retaliation for imposing sanctions on the authoritarian government for a brutal internal crackdown on dissent.
Thousands were jailed and beaten following months of protests after Lukashenko won a sixth term in a 2020 election that the opposition and the West saw as rigged.
The EU is calling for humanitarian aid as up to 4,000 migrants are stuck in makeshift camps in freezing weather in Belarus while Poland has reinforced its border with 15,000 soldiers, in addition to border guards and police.
The EU has expressed solidarity with Poland's guarding the bloc's external border.
“What we have been witnessing recently, as you've said, is a very well orchestrated, prepared by the Belarusian regime, operation where the people are instrumentalized,” said Marcin Przydacz, Poland's deputy foreign minister.
"It is a very cynical game where the people are, as I said, used us as bullets," he added.
Belarus' borders with Poland, Lithuania and Latvia are also the eastern borders of both the EU and NATO.
The EU says Lukashenko's authoritarian regime has for months invited migrants to the Belarusian capital of Minsk, many of them Iraqis, Afghanis and Syrians, with the promise of helping them across the border.
Meanwhile, Lithuanian officials said they were seeing a rising number of attempts by migrants to cross its border from Belarus.
The 27-country EU has already imposed four sets of sanctions on Belarus authorities and senior officials over the disputed election last year that returned Lukashenko to office and his government's brutal crackdown on peaceful protesters.
The EU is preparing a fifth lot of sanctions on Belarus.
On Monday the bloc’s foreign ministers extended the scope of those measures to add airlines, travel agents and others accused of helping to bring migrants to Minsk.
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