"The transfer of foreigners to Poland by the German police was carried out in violation of the principles of cooperation between the two services and against the transfer law. The German authorities must not make such a decision arbitrarily," Poland's border service wrote on social media on Monday.

The statement came after German authorities reportedly deposited a family of five Afghan asylum seekers on the Polish side of their border near Osinow Dolny last Friday after apprehending them for having illegally entered Germany without the necessary paperwork.

Under existing law, their lack of documents dictated they be returned to Poland, where they had received asylum.

Tusk to discuss incident with Scholz 

Prime Minister Donald Tusk said he would be discussing the "unacceptable incident" with German Chancellor Olaf Scholz at this week's informal EU gathering in Brussels.

It will also be discussed at the next meeting between Polish Interior Minister Tomasz Siemoniak and his German counterpart, Nancy Faeser, according to a Polish ministry spokesman.

Polish authorities complained the Germans had not informed them of their intentions of dropping off the Afghans.

The Germans say that although they tried to organize a handover they decided to simply leave the family after getting "no response from the Polish side for several hours."

js/lo (AFP, dpa)