The border guard service said on its Telegram channel that "checks have been stepped up" and "tactical reinforcements have been deployed", but that "checkpoints are permitting people to enter and leave".

Lukashenko, a strongman who has ruled for 26 years, had told a women's forum Thursday that "half" of the Belarusian army would be deployed to the borders with Lithuania, Latvia, Poland and Ukraine.

The frontiers themselves would be closed in view of the threat of a "hot war", he added.

"I don't want our country to enter a war, and even less for Belarus, Poland and Lithuania to become the scene of military actions, where other people's problems would be sorted out," Lukashenko said.

Lithuanian Prime Minister Saulius Skvernelis rubbished Lukashenko's talk of war, calling it "noise", and highlighting that "no decision" had been taken to close the borders.

Any closure "would hurt the Belarusian economy and people first of all," Skvernelis added.

A NATO source told AFP that the alliance had not stepped up its military presence in member countries bordering Belarus, adding that it poses "no threat" to Minsk.

Since claiming a landslide re-election victory in August 9 polls, the man sometimes called "Europe's last dictator" has faced massive street protests demanding he step down.

His government claims the opposition movement is being used as a puppet by Western countries.

Lukashenko has deployed the army to Belarus' borders several times faced with supposed foreign threats, most recently pointing his soldiers towards Russia over the summer.

While before the election he accused Moscow of wanting him gone to more easily subjugate Belarus, Lukashenko has U-turned since the vote, leaning on President Vladimir Putin for support against the protesters.

Russia has promised to help and blamed the West led by the US for the protests.

Historically close allies since the breakup of the Soviet Union, Minsk and Moscow are currently carrying out joint military exercises including close to the Polish border dubbed "Slavic Brotherhood 2020".