Poland’s parliament has passed a legal amendment allowing border guards to immediately expel migrants who cross the border illegally.
Guards will also be given power to refuse applications for international asylum, without examination.
Human rights groups accuse Poland of wanting to legalise migrant pushbacks.
Under international law, anyone seeking international protection must be given access to the asylum process, even if they have crossed a border illegally.
It is forbidden to send people back to where their wellbeing may be in danger.
The newly approved legal amendment must now be signed into law by President Andrzej Duda, an ally of the government.
Poland and fellow EU states Lithuania and Latvia have seen massive increases in migrants from Middle Eastern and Asian countries trying to enter illegally since the start of the summer.
Since August, there have been more than 16,000 attempts to cross the border from Belarus illegally compared with just 120 for the whole of last year, Poland’s border agency has said.
At least six migrants have been found dead near the border with temperatures now falling below freezing overnight.
Poland and the EU have accused Belarus’s authoritarian President Alexander Lukashenko of facilitating the migrant influx as a form of retaliation against sanctions.
Belarus has been accused of inducing migrants to fly there on the false promise of legal entry to the EU.
The Belarusian government has denied the allegations and blames Western politicians for the situation on the border.