The European Union's border agency announced on Saturday that it will "significantly increase" its support to Lithuania next week to help man the border with Belarus.
Frontex said in a statement that it will more than double its number of officers and patrol cars in Lithuania.
"Lithuania's border is our common external border and Frontex stands ready to help where needed," the agency's Executive Director Fabrice Leggeri said in a statement.
"We are speeding up and beefing up what was already planned. And in close cooperation with the Lithuanian authorities we are preparing furthermore a Rapid Border Intervention," he added.
Lithuania President Gitanas Nauseda thanked Frontex in a tweet. He also said that the agency would also send helicopters, and interpreters.
The reinforcements come after Lithuania accused Belarus of letting illegal migrants through their shared borders in retaliation against EU sanctions against the regime of President Alexander Lukashenko.
Brussels has taken measures against Belarus for the fraudulent August 2020 presidential election, the subsequent crackdown on pro-democracy protests and the May 2021 forced landing of a flight to arrest a pro-opposition journalist.
Belarus has denied Lithuania's allegations.
Official figures from Lithuania show that more than 410 migrants illegally crossed the border in June — more than the total number who crossed over the previous four years combined.
Lithuania has declared a state of emergency over the rise in migration and began building a fence along the border earlier this week to deter the flow.