Poland said Wednesday it had seen a surge in attempts to breach its border and had pushed back hundreds of migrants to Belarus, after it accused Minsk and Moscow of trying to orchestrate a crisis on Europe's borders.
The migrants, mainly from the Middle East, have spent days in freezing temperatures on the border, blocked by rows of Polish border guards behind razor-wire.
Western governments have accused Belarusian strongman Alexander Lukashenko of luring the migrants to his country and sending them to cross over into EU member Poland in retaliation for sanctions.
Poland has gone a step further, saying Lukashenko's main backer, Russian President Vladimir Putin, is masterminding the crisis.
Between 2,000 and 4,000 migrants, reported to be mainly Kurds, have set up a camp near the border after they made a concerted effort to cross on Monday but were pushed back by Polish border guards.
Polish officials said Wednesday there had been a spike in attempted crossings in the previous 24 hours.
Poland's border guard said that large groups of migrants, ranging from 200 to several dozen persons, crossed the border illegally from Belarus in three places overnight in Podlaskie province, but were all pushed back.
"All these attempts were thwarted, all these people were redirected back to Belarus," Podlaskie region border guard spokeswoman Major Katarzyna Zdanowicz told reporters.
Polish police said more than 50 migrants were detained and handed over to border guards to be sent back to Belarus.
- 15,000 Polish troops -
"The situation is not calm," Defence Minister Mariusz Blaszczak told Polish radio.
"Now we are dealing with smaller groups, although numerous, which are simultaneously attacking the Polish border in several places," he said.
The 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.
Blaszczak said on Twitter that 15,000 troops had been deployed along with police and border guards "to protect our homeland from the attack of the Lukashenko regime."
Belarus has levelled its own accusations against Poland, saying Warsaw is violating international norms by blocking the migrants and beating them back with violence.
Its border service said that four Kurds had been severely beaten by Polish guards and that Polish military forces were firing over the heads of migrants attempting to cross.
Journalists have been blocked from areas close to the border, but in the nearby town of Sokolka AFP reporters saw a patrol stopping vehicles to check the trunks for migrants, as well as several military trucks and police vans driving out of the town.
Polish Prime Minister Mateusz Morawiecki on Tuesday said the migrants were being used as "human shields to destabilise the situation in Poland and the EU" and pointed the finger at Russia.
"This attack which Lukashenko is conducting has its mastermind in Moscow, the mastermind is President Putin," Morawiecki told the Polish parliament.
The European Union, NATO and the United States have all said Lukashenko is provoking the crisis in response to Western sanctions imposed over his heavy crackdown on the opposition following a disputed election last year.
- Merkel calls Putin -
The EU is now considering new sanctions for human trafficking and EU chief Charles Michel was due to hold talks on the crisis with Mateusz Morawiecki in Warsaw later Wednesday.
German Chancellor Angela Merkel telephoned Putin to ask him to get Belarus to stop the "inhumane" instrumentalisation of migrants, her spokesman said Wednesday.
Belarus and Moscow have hit back at the accusations, saying the West should deal with migrant flows caused by its military interventions in the Middle East.
The Kremlin said Wednesday it was "irresponsible" for Poland to blame Putin for the crisis, while Belarus's foreign minister said the EU was causing the crisis because it wanted a reason to impose new sanctions.
"The migrant crisis was provoked by the EU itself and its states that border Belarus," Vladimir Makei said on a visit to Moscow to meet his Russian counterpart Sergei Lavrov.
Lavrov, who has said the EU should provide financial aid to Belarus to deal with migrants, like it did for Turkey, reiterated Russian support for its ally.
Accusing Western institutions of mounting an "anti-Belarusian campaign", Lavrov said Russia and Belarus had "closely coordinated our approaches" to countering it.
In a show of force, Russia's defence ministry said two of its Tu-22M3 long-range bombers had flown over Belarus Wednesday as part of longstanding efforts at military integration.
Thousands of migrants have crossed or attempted to cross from Belarus into the eastern EU member states of Latvia, Lithuania and Poland in recent months.
Lithuanian lawmakers voted Tuesday to impose a state of emergency along the Belarus border, effective from midnight.