WARSAW, POLAND — Polish border officials reported on Friday that over 180 migrants successfully entered Poland by navigating through a clandestine tunnel concealed within a forested area along the Belarus border.

Out of these individuals, approximately 130 were apprehended by Polish authorities following the discovery of the passage on Thursday, while the remainder have yet to be located, according to a statement from the Polish Border Guard.

The agency released footage showcasing the tunnel, which was carved through tree roots and exposed earth. The structure, measuring only about 5 feet in height, was reinforced with wooden beams and metal rods, requiring most individuals to crouch in order to pass through.

Since 2021, Poland, a member of the European Union, has been confronting a migrant crisis along its border with Belarus.

Polish officials have accused Belarus, along with its ally Moscow, of orchestrating efforts to destabilize Poland by facilitating the movement of migrants, primarily from the Middle East and Africa, across the border.

Belarus and Russia have repeatedly dismissed these accusations.

The border guard said it was the fourth tunnel it had discovered in the western region of Podlaskie this year.

Guards also detained a 69-year-old Pole and a 49-year-old Lithuanian who had arrived to pick up the migrants, it added.

The “hidden entrance in the forest was located approximately 50 metres (from the border fence) on the Belarusian side of the border, while the exit was located approximately 10 metres from the barrier on the Polish side,” the Border Guard said.

Officers used electronic systems to work out how many people passed through, and army and police had joined the search for the missing migrants, it added.

Poland started work on its 180km (110-mile) border fence in 2022.