Leaders in some European countries neighboring Belarus have raised security concerns as the founder of the Wagner mercenary group is believed to have arrived in Belarus after aborting his mutiny in Russia.

A state-run news agency in Belarus reported Tuesday that President Alexander Lukashenko had revealed Yevgeny Prigozhin is in the country.

Lukashenko also reportedly said he has offered Wagner fighters the use of an abandoned base in his country.

A Russian independent media outlet said new camps for Wagner troops are being built in Belarus.

A US think tank, the Institute for the Study of War, said Tuesday that Lukashenko is likely seeking to use the Wagner Group in his country to balance against Moscow's bid to absorb Belarus through the establishment of a union state.

Polish President Andrzej Duda said Tuesday that the relocation of Wagner mercenaries to Belarus would send "negative signals."

He indicated he would raise concerns with other NATO leaders when they meet, and called for strengthening NATO's eastern flank, particularly in the Baltic states and Poland.