Thousands of people demonstrated in Warsaw on Sunday against pushbacks of migrants at the Polish-Belarusian border.
Demonstrators marched through the Polish capital's centre bearing signs like "Stop torture at the border" and "Nobody is illegal".
Thousands of migrants, most from the Middle East, have attempted the crossing from Belarus into European Union countries Poland, Latvia and Lithuania in recent months.
Eyewitness accounts from migrants and reports from aid groups accuse Poland of pushbacks - the practice of turning people back across the frontier into Belarus.
Warning that pushbacks risk condemning migrants to freeze to death, some demonstrators in Warsaw waved banners made of thermal blankets often handed out by aid groups.
Smaller rallies were held in other Polish cities, local media reported.
Seven people have died at the EU's eastern border since the increase in migrant arrivals that began in summer, according to Polish, Lithuanian and Belarusian authorities.
On Thursday, Poland's parliament altered the law to make pushbacks legal and allow officials to ignore asylum requests made by people who had entered the country illegally.
Lawmakers also approved government plans to build a border wall at an estimated cost of €353 million.
Aid groups have criticised Poland for declaring a state of emergency at the border, blocking them from helping migrants and barring access to non-residents - including journalists.
Meanwhile Brussels has accused Belarus of deliberately organising the increased border crossings, as retaliation for sanctions imposed by the EU over Minsk's repression of its opposition movement.
Migrants arriving there are waved through to the EU borders and are held under watch by Belarusian border guards on one side and Polish, Lithuanian or Latvian officers on the other.
Last month the UN refugee agency and the International Organization for Migration said they were "shocked and dismayed" by migrant deaths at the border.
"Groups of people have become stranded for weeks, unable to access any form of assistance, asylum or basic services," they said.
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