Polish PM accuses Minsk of "state terrorism" as Belarus warns Warsaw of violating internation norms in its treatment of migrants.
EU and NATO member Poland says it has seen a surge in attempts to breach its border and pushed back hundreds of migrants to Belarus, accusing Minsk of "state terrorism" by provoking a new migrant crisis in Europe.
"What we are facing here, we must be clear, is a manifestation of state terrorism," Polish Prime Minister Mateusz Morawiecki told reporters in Warsaw at a press conference with visiting EU chief Charles Michel.
Belarus has levelled its own accusations against Poland, saying Warsaw is violating international norms by blocking the migrants and beating them back with violence.
Belarus's foreign minister accused the EU of "provoking" a migrant stand-off on its border with Poland and said Minsk was seeking a "joint response" to the crisis with Russia.
"The migrant crisis was provoked by the EU itself and its states that border Belarus," Foreign Minister Vladimir Makei said on a visit to Moscow.
He added that Belarus was hoping for "mutual support" from neighbouring Russia, "including a joint response regarding unfriendly actions against our country".
The Polish Defence Ministry said Belarus was using intimidation to force migrants to breach the border, tweeting two short videos that it said showed a shot fired on the Belarusian side by a man in uniform.
Michel said new sanctions against Belarus "are on the table" and that EU members would consult on the issue on Monday.
EU fury over Lukashenko
Migrants have been trying to cross the border for months, but the crisis reached a new level when hundreds made a concerted effort on Monday and were pushed back by Polish border guards.
They set up a camp on the border, living in tents and burning wood from local forests to keep warm, blocked by Polish guards behind razor-wire.
Western governments for months have accused the Belarusian regime of luring migrants from the Middle East to Belarus to send them across the border to the European Union in retaliation for sanctions.
The EU's relationship with Minsk has deteriorated sharply since August last year when Belarusian leader Alexander Lukashenko cracked down on anti-government protesters in the wake of elections the opposition said were rigged.
Western countries have imposed a range of sanctions over the crackdown and say they are considering new action over the migrant crisis.
Russia has buttressed Lukashenko's regime with security guarantees and large loans to aid the struggling Belarusian economy.