"We see three larger groups along the border: two groups of twenty people each and one group of about forty," Laurynas Kasciunas, chairman of the parliamentary Committee on National Security and Defense, told reporters.
"That thousand [migrants] may be approaching, but they are not concentrated in one place yet. We do not have such information," he added.
To his knowledge, Belarusian officers are near one of these groups.
"They are trying to create that trap situation," Kasciunas said. "This means that [...] a tent camp may emerge on our border [...] and we need to prepare."
Thousands of migrants have already set up a makeshift camp on the Belarusian side of the border with Polish after failing to push their way through the border.
Lithuania on Wednesday declared a state of emergency along its border with Belarus to prepare for a possible scenario.
Kasciunas said that Lithuania is not considering scrapping its policy of pushing migrants back to Belarus, but it could provide aid to migrants stranded at the border.
The parliamentarian commented on a report by the Brussels-based news website EUobserver that the European Commission would likely demand that Poland, Latvia and Lithuania amend their laws that allow pushing migrants back to Belarus.
"If Brussels, if the commissioners decide to propose some changes, let them fly in planes, take all migrants from Belarus and fly with them back to Brussels," he said. "Lithuania will continue its pushback policy. There is no question about that."
To change the laws, the European Commission should propose a sustainable solution to fly migrants directly from Belarus back to their countries of origin, according to the MEP.
Over 4,200 irregular migrants, mostly Iraqi citizens, have crossed into Lithuania from Belarus illegally so far this year.
Lithuania and other Western countries accuse the Minsk regime of orchestrating the unprecedented migration influx, calling it "hybrid aggression".