Lithuania has accused Belarusian border guards of illegally crossing the border to push a group of migrants into Lithuanian territory.
The interior ministry said a dozen guards had forced 35 migrants to cross into Lithuania's southeast Šalčininkai District, south of the capital Vilnius.
A video of the alleged incident near the village of Dieveniskes was published on social media by the Lithuania's border protection service.
The footage purports to show a number of guards, armed with shields, standing behind a group of people as they make their way through high grass.
Lithuania says it is "not the first incident of its kind" at the border with Belarus in recent days, and claims that Belarusian border guards withdrew to their country's territory after repeated warnings.
"We cannot tolerate this bold provocation of twelve Belarusian officials crossing the border of the Republic of Lithuania today," said Interior Minister Agnė Bilotaitė said in a statement.
"We have immediately responded to the provocation and have made a decision to further increase the border protection capacity," Bilotaitė added.
Lithuania said they had launched an investigation into the incident and had informed Belarus' State Border Committee.
The European Union has accused Belarus of deliberately facilitating the migration of Iraqi refugees into Lithuania and the bloc, in retaliation against sanctions imposed on Minsk.
Belarus’s border committee has also released a video of the incident from its side of the border, which does not show the officers in riot gear.
"Lithuanian security forces use physical force to try to push the refugees into the territory of the Republic of Belarus," it stated.
"Lithuanian border guards deliberately ignore all requests for asylum," the statement added.
The incident comes as EU interior ministers are due to meet in Brussels to discuss further action on the migration issue.
Lithuania says it has already detained 4,124 irregular migrants in 2021, compared to just 74 in the whole of 2020.
Vilnius has declared a state of emergency to address the sharp rise in migration, which it says Belarusian authorities are encouraging.
Last month, the country’s parliament voted to build a fence on the Belarus border to stop Iraqis, Afghans, and other non-EU migrants from entering.