The United Nations Security Council will hold an emergency meeting Thursday on the migrant crisis at the Polish-Belarusian borders at the request of Estonia, France, and Ireland, diplomats said Wednesday.

The calls for an emergency meeting came as thousands of migrants are stuck along the border between Poland and Belarus.

Poland has been accusing Belarus of "state terrorism" over migrants row, as Warsaw believes Minsk is behind the surge in migrants trying to access the European Union in a bid to destabilize the bloc.

The 15-member council will meet behind closed doors for a session on Thursday as tensions between the two states are at their highest.

The West has been accusing Belarusian President Alexander Lukashenko of luring migrants to his country and sending them to cross into Poland in retaliation for western sanctions the EU imposed on his country.

"Such situations should not be used for political purposes and become a cause of tension between states," UN spokesman Stephane Dujarric said.

"The secretary-general is following with concern the situation in the Belarus-Poland border," the spokesman added.

The spokesman also underscored the importance of using humanitarian principles and international law to deal with migration and refugee issues.

Russia sends 2 nuclear-capable bombers to Belarus

Russia undertook a rare step of sending two nuclear-capable strategic bombers to patrol Belarus' airspace on Wednesday, in a sign of support for its close ally. Belarus has been embroiled in a migrant standoff with the EU.

Moscow's decision to escalate the situation came as the 27-nation European Union considered Belarus' actions as a legal basis for additional sanctions. The sanctions could be implemented as soon as next week and aim at more than 30 individuals and entities, including Belarus' foreign minister and its national airline.

Poland asked NATO for help

In a closed-door conference, Poland briefed fellow NATO countries about the situation. From their part, NATO countries pledged their support, according to an alliance official. Poland had already mobilized 10,000 soldiers to its frontier with Belarus.

Belarus was accused of mounting a "hybrid attack" by sending migrants across the border into Poland by the European Union on Wednesday, clearing the path for tougher sanctions against Minsk in a crisis that threatens to engulf Russia and NATO.

Belarusian President Alexander Lukashenko and Russian President Vladimir Putin deemed the European Union accountable for the situation.