Lithuania has closed two of its six border checkpoints with Belarus in a move it announced earlier this month citing the security risk posed by Russia's Wagner mercenary group.

"Both Sumsko and Tvereciaus border checkpoints were shut at midnight," the spokeswoman of the border guard service Lina Laurinaityte-Grigiene told AFP news agency on Friday.

Officers laid road spikes at the closed checkpoints and will erect fences with barbed wire in the area, she added.

Lithuania, a member of NATO's eastern flank, responded to escalating tensions between the neighbours, with Vilnius warning of a provocations threat by Minsk.

But the officials in Vilnius said the decision will also help control smuggling, as the remaining four border checkpoints have x-ray systems to detect illegally transported goods, mainly cigarettes.

The decision is also meant to curb travelling across the border for shopping or family visits.

In the first half of 2023, Lithuanian citizens crossed the border with Belarus 230,000 times.

But Vilnius has been warning that Minsk may try to recruit those travellers for espionage, exert psychological pressure, or even blackmail them by performing checks on their phones and social media.

The Lithuania-Belarus ties had been tense for years, but they further deteriorated after Belarusian 2020 presidential elections, widely slammed as rigged.

Belarus criticised the decision to close checkpoints, calling it "far-fetched".

"Lithuania, by taking such decisions, purposefully and deliberately creates artificial barriers on the border to serve its political ambitions," Belarus' border force said on social media Wednesday.

Both Poland and Lithuania have erected fences on their borders with Belarus and Russia.

Mercenaries from Russia's Wagner group have been taking refuge in Belarus since their failed mutiny against Russia's military leadership in June.

Their presence in Belarus has sparked alarm among Minsk's western and northern neighbours.

Poland has said it will bolster its eastern border with 4,000 troops supporting the national border agency and another 6,000 in reserve.

Poland and the three Baltic countries, all NATO members, are some of Ukraine's staunchest allies against Russia and have hosted outspoken critics of longtime Belarus leader Alexander Lukashenko.