The first part of the wall will be 500 meters long and 1.8 meters high, with barbed wire on top, according to Ruta Montvile, spokeswoman for Lithuania's defense chief.
EU member Lithuania recently declared a national emergency due to the increasing number of people crossing the border from Belarus.
Several hundred people have been arrested, a migrant flow that Vilnius accuses the Minsk regime of being behind.
Accused of using migration as a weapon
In a speech at the end of May, Belarusian dictator Alexander Lukashenko said that migrants in Belarus would no longer be prevented from entering the EU illegally, prompting Lithuanian Foreign Minister Gabrielius Landsbergis to accuse the Belarusian president of "using migration. as a weapon ”.
The President of the European Council, Charles Michel, agrees.
He recently condemned Minsk's actions.
"Belarusian authorities are using irregular migration to put pressure on the EU and Lithuania," Michel said in a statement condemning Belarus' actions, according to Reuters.
Finnish aid to borders Belarus
The European Border and Coast Guard Agency Frontex has asked EU member states to help Lithuania, which is what Finland is now responding to with patrols going down on 14 July and staying until 1 December.
Four border guards and two vehicles will be sent from Finland to the Latvian and Lithuanian border areas with Belarus.