Polish border authorities say more than 180 migrants crossed illegally into Poland through a hidden tunnel dug beneath the border with Belarus, highlighting renewed pressure along the country’s eastern frontier.

According to the Polish Border Guard, the tunnel was discovered on Thursday in a forested area near the border. By Friday, approximately 130 migrants had been detained on Polish territory, while several dozen others remained unaccounted for and were believed to be on the run.

Officials released video footage showing the narrow underground passage carved through roots and compacted soil. The tunnel was reinforced with wooden posts and metal rods and measured roughly five feet in height, forcing most individuals to crouch as they passed through. Authorities said the structure was concealed beneath dense forest cover, making detection difficult.

The incident represents one of the largest single illegal crossings reported in recent months and underscores ongoing security challenges along the Poland–Belarus border. Polish officials have repeatedly accused organized networks of facilitating illegal crossings in the area, amid heightened regional tensions.

Border Guard units continue to search the surrounding area as investigations focus on how the tunnel was constructed and how long it had been in use. Officials said additional security measures may be implemented to prevent similar breaches in the future.