The attack happened two days ago near Czeremcha after officers detained 10 migrants.
Stones and a petrol bottle followed, exploding close to the patrol; no one was hurt, the Border Guard said.
Siemoniak told public radio the incident would not have occurred without Belarusian involvement and that Warsaw would take “strong diplomatic steps” after the protest filed via liaison officers.
He denied Germany was pushing migrants back into Poland, saying only the readmission procedure now applies to foreigners, many of them Ukrainians, who hold Polish but not German residence papers.
Poland re‑introduced temporary checks on its borders with Germany and Lithuania more than a week ago amid what it says are rising illegal crossings.
(jh)
Source: IAR