Lithuania on Friday closed two more border checkpoints with Belarus, a key ally of Russia, due to security concerns stemming from the war in Ukraine and activity by the Minsk government.

The Baltic state, which shelters many Belarusian opposition activists and is a staunch Ukraine supporter, closed two crossings last year after ercting a barrier along the border.

"We have taken steps to restrict the movement of people, goods and transport, with four of the six border checkpoints with Belarus now closed," Interior Minister Agne Bilotaite told AFP.

"The precarious neighbourship with Russia, which has launched a military aggression in Ukraine, and its ally Belarus, whose undemocratic regime has used migrants as a tool of political pressure against Lithuania, makes it necessary to take additional security measures."

Bilotaite said her country of 2.7 million people -- an ex-Soviet nation now part of the European Union and NATO -- had been "witnessing increased activity of Belarusian and Russian intelligence services" on its territory.

Checkpoints at Medininkai and Salcininkai will remain open but pedestrians and cyclists will be banned.

Lithuanian border guards have reported that nearly 390,000 Belarusian citizens crossed the border last year, around 50 percent more than in 2022.

Most of these Belarusians had EU travel documents issued by Poland, according to the border guards.

Lithuania's ties with Belarus have been tense for years, but deteriorated after the 2020 Belarusian presidential elections, that opponents said were rigged.

Lithuania has since hosted exiled opposition leader Svetlana Tikhanovskaya and fellow activists, as well as tens of thousands of other Belarusian citizens.

Lithuanian intelligence warned last year that members of the Belarusian diaspora were being recruited by the Belarusian KGB while travelling between the countries and on social media.

In 2021, Lithuania, Latvia and Poland saw an unprecedented influx of illegal migration from Belarus, with thousands of people -- mainly from the Middle East and Africa -- crossing their borders into the European Union.

The West accused the Belarusian government of orchestrating the influx, which Minsk has denied.