Nato members Poland and the Baltic states will seal off their borders with Russia’s ally Belarus in the event of any military incidents or a massive migrant push by Minsk, the countries’ interior ministers warned on Monday.

The ministers said they were seeing growing tensions on Nato’s and the European Union’s borders with Belarus, which has taken in thousands of Russia’s military mercenaries and is pushing Middle East and African migrants into Europe, despite various forms of barriers having been put up.

They warned of swift and concerted response in the case of a military incident or large migrant push.

The ministers of Poland, Lithuania, Latvia and Estonia addressed the media following their talks in Warsaw.

In a joint statement they demanded that the government of Belarus president Alexander Lukashenko immediately remove from its territory the Wagner Group mercenaries.

They also demanded the removal of migrants from border areas and their return to their home countries.

Interior iinister Mariusz Kaminski of Poland said that any “critical incident” involving the military or an influx of migrants to Poland and the Baltic states from Belarus would be met with an immediate response and the shutting of all border crossings to travellers and to goods.

He said steps have been developed to continue supporting members of the political opposition in Belarus in such a situation, but he gave no details.

Lithuania recently temporarily closed two of its six border crossings with Belarus.

The four countries, which are also European Union members, support Ukraine in its fight against Russia’s invasion and also support the opposition in Belarus.

Poland and Lithuania border Belarus and Russia’s exclave of Kaliningrad, Latvia borders Belarus and Russia, and Estonia borders Russia.

Latvia’s interior minister, Lauri Laanemets, said Tallin supports the group’s decisions, which could also apply to its border with Russia.

The sudden death of mercenary leader Yevgeny Prigozhin in a plane crash in Russia last week has raised questions about the future of the Wagner group, which Poland’s interior minister Mariusz Kaminski branded as “extremely dangerous” and “demoralized”.

He also said the mercenaries pose a threat to the citizens of Belarus and the entire region.

Russia’s president, Vladimir Putin, has ordered the Wagner fighters to sign an oath of allegiance to the Russian state, according to a decree published on the Kremlin’s website on Friday and effective immediately.

Also last week, Poland’s president, Andrzej Duda, confirmed that Russia has begun shifting some short-range, nuclear weapons to neighbouring Belarus, a move that he said will change the security architecture of the region and the entire Nato military alliance.