By Dmitry Antonov and Robin Emmott
MOSCOW/BRUSSELS (Reuters) - The European Union accused Belarus on Wednesday of mounting a "hybrid attack" by pushing migrants across the border into Poland, paving the way for widened sanctions against Minsk in a crisis that threatens to draw in Russia and NATO.
Russia took the rare step of dispatching two nuclear-capable strategic bombers to patrol Belarusian airspace in a show of support for its close ally. Poland briefed fellow NATO allies at a closed-door meeting and they pledged their support, an alliance official said.
Migrants from the Middle East, Afghanistan and Africa trapped in Belarus made multiple attempts to force their way into Poland overnight, Warsaw said, announcing that it had reinforced the border with extra guards.
U.N. human rights chief Michelle Bachelet called on states to reduce tensions and resolve the "intolerable" crisis.
"These hundreds of men, women and children must not be forced to spend another night in freezing weather without adequate shelter, food, water and medical care," she said.
The EU, which has repeatedly sanctioned Belarus for human rights abuses, accuses Minsk of luring migrants from war-torn and impoverished countries and then pushing them to cross into Poland to try to sow violent chaos on the bloc's eastern flank.
"We are facing a brutal hybrid attack on our EU borders. Belarus is weapon migrants' distress in a cynical and shocking way," EU Council President Charles Michel said.
The bloc's 27 ambassadors agreed this constituted a legal basis for further sanctions, which could come as early as next week and target some 30 individuals and entities including the Belarusian foreign minister and the national airline.
"Very rapidly at the beginning of next week there will be a widening of the sanctions against Belarus," European Commission President Ursula von der Leyen told reporters after a meeting with U.S. President Joe Biden in Washington.
"We will look into the possibility of sanctioning those airlines who facilitate human trafficking towards Minsk and then the EU-Belarus border," she added.
Biden and von der Leyen addressed the humanitarian situation on the European Union's border with Belarus and expressed "deep concern about the irregular migration flows", the White House said. Separately, U.S. Secretary of State Antony Blinken said: "The idea that Belarus would weaponize migration is also profoundly objectionable."
He said Washington will keep pressure on Belarus President Alexander Lukashenko "as long as the regime is refusing to respect its international obligations, or commitments, as long as it's undermining peace and security in Europe through its actions and as long as it continues to repress and abuse people..."
Lukashenko and Russian President Vladimir Putin have pinned the blame on the EU.
The Kremlin accused Europe of failing to live up to its own humanitarian ideals and trying to "strangle" Belarus with plans to close part of the frontier. Moscow said it was unacceptable for the EU to impose sanctions on Belarus over the crisis.
The crisis strikes the EU in a vulnerable area.
In 2015, the bloc was deeply shaken by an influx of over a million people fleeing conflict in Syria, Iraq and Afghanistan that led to deep rifts between member states, strained social security systems and fanned support for far-right parties.
The EU appears more united this time but there are signs of internal friction: some in Brussels have warned Poland that it should not use EU funds to erect border walls and razor wire while others argue the bloc needs to help defend its borders. Michel said on Wednesday the EU needed to make up its mind.
Compared with 2015, the current crisis has an added geopolitical dimension as it is unfolding on the dividing line between NATO to the west and Russia-allied Belarus to the east.
The Tupolev Tu-22M3 bombers that Russia sent to overfly Belarus are capable of carrying nuclear missiles, including hypersonic ones of the kind designed to evade sophisticated Western air defences.
Russian Foreign Minister Sergei Lavrov said he hoped responsible Europeans would "not allow themselves to be drawn into a spiral that is fairly dangerous".
German Chancellor Angela Merkel told reporters she urged Putin in a phone call to use his influence on Lukashenko "because people (migrants) are being used, they have become, so to speak, victims of an inhumane policy - and something has to be done about it".
The Kremlin said Putin told Merkel that the EU should talk directly to Belarus.
Thousands of people have converged on the border this week, where makeshift razor wire fences and Polish soldiers have repeatedly blocked their entry. Some of the migrants have used logs, spades and other implements to try to break through.
"It was not a calm night. Indeed, there were many attempts to breach the Polish border," Defence Minister Mariusz Blaszczak told broadcaster PR1.
Video from the border obtained by Reuters showed young children and babies among the people stuck there.
"There are lots of families here with babies between two and four months old. They have not eaten anything for the past three days," the person who provided the video told Reuters, saying they were a migrant themselves and declining to be identified.
Some migrants have complained of being repeatedly pushed back and forth by Polish and Belarusian border guards, putting them at risk of hypothermia, lack of food and water.
Syrian migrant Youssef Atallah said he feared he would die in the forest at the border after being stranded for days, unable to breathe through his nose after it was broken in what he said was an assault by a Belarusian soldier.
Atallah, who finally reached safety in a migrant centre inside Poland on Wednesday, described almost giving up after being blocked in both directions at the border.
"We told (Belarusian guards) we want to go back to Minsk, we don't want to continue this trip," he told Reuters. "They told us there is no going back to Minsk for you. Just go to Poland."
(Reporting by Dmitry Antonov in Moscow and Robin Emmott in Brussels; Alan Charlish in Suprasl, Poland; Kacper Pempel and Felix Hoska in Hajnowka, Poland; Joanna Plucinska, Anna Koper and Pawel Florkiewicz in Warsaw; Andrius Sytas in Kapciamiestis, Lithuania; Kirsti Knolle and Michael Nienaber in Berlin; Maria Kiselyova in Moscow; Matthias Williams in Kyiv; Jeff Mason and Andrea Shalal in Washington; Writing by Matthias Williams, Andrew Osborn and Mark Trevelyan; Editing by Philippa Fletcher, Nick Macfie, Mark Heinrich and Grant McCool)