WARSAW, Aug 3 (Aljazeera) - Fighters from Russia’s private Wagner mercenary force are being moved close to NATO’s eastern flank to destabilise the military alliance, according to Poland’s prime minister.

Wagner soldiers have begun training with the Belarus national army, prompting Poland to start moving more than 1,000 troops closer to the border. On Tuesday, it accused Belarus of violating its air space with military helicopters.

“We need to be aware that the number of provocations will rise,” Mateusz Morawiecki said on Thursday after meeting Lithuanian President Gitanas Nauseda in eastern Poland.

“The Wagner group is extremely dangerous and they are being moved to the eastern flank to destabilise it.”

The politicians met in the Suwalki Gap, a sparsely populated but strategically important area of Polish territory between Belarus and the Russian exclave of Kaliningrad that joins the Baltic states to other NATO members.

Nauseda said the number of Wagner fighters in Belarus could be higher than 4,000.

“We must not only talk about measures at the national level but also … what should be done if this situation becomes even more complicated, including the closure of the border with Belarus,” Nauseda said.

“This should be done in a coordinated manner between Poland, Lithuania and Latvia.”

Laurynas Kasciunas, chairman of the Seimas National Security and Defence Committee, told reporters that Wagner mercenaries in Belarus with their current combat power do not pose a conventional military threat.

Whether they pose a great threat in the future, he said, “will depend on further scenarios, how they are armed and their orders”.

In Poland, some critics of the government believe that it is overstating the threat in order to present itself as tough on security before parliamentary elections later this year.

Polish opposition leader Donald Tusk accused the ruling party of using Wagner to stoke fear before the elections, something the party has denied.

The United States ambassador to the United Nations, Linda Thomas-Greenfield, said earlier this week that the US views the Wagner Group – whose forces have fought in Ukraine and also operated in Africa – as a threat.

“We have seen their malign efforts on the continent of Africa. So we certainly worry that this group, at the behest of the Russian government – because they do not work independently of the Russian government – is a threat to all of us,” Thomas-Greenfield told reporters on Monday.

“And we have to ensure that the message is clear that any attacks by the Wagner Group will be seen as an attack by the Russian government.”

Belarus allowed Russian President Vladimir Putin to use its territory as a launch pad for the Ukraine invasion but has not committed its own troops to the war.