Poland has launched a large-scale security operation on its border with the Russian exclave of Kaliningrad, deploying police, border guards and the army.
Prime Minister Donald Tusk said Polish and allied intelligence services had warned of a possible incursion by armed individuals, as well as acts of sabotage and provocations along the border in the first days of November.
According to Tusk, suspicious movements of people with flashlights near the border were observed shortly after midnight, but the rapid intervention of security forces prevented the provocations. He warned of rising tensions with Russia and called for heightened vigilance.
Poland shares 232 kilometres of border with Kaliningrad, a heavily armed Russian territory between Poland and Lithuania.