Tensions between Poland and Germany have risen after the authorities in Warsaw approved the deployment of 5,000 soldiers along the country's frontier with Germany, in a bid to stop failed asylum seekers being sent back to the country.

Personnel, potentially backed up by surveillance drones, will also be put in place at the border with Lithuania, but it is with Germany that there is greater disagreement over the issue, following the recent change of government in Berlin.

"We consider the temporary restoration of controls at the Polish-German border necessary to limit and reduce to a minimum the uncontrolled flows of migrants back and forth," said Poland's Prime Minister Donald Tusk.

Germany and Poland are just two of the European countries that have brought back elements of border controls in response to public concern about undocumented migration, despite being part of the 29-nation Schengen zone, which permits passport-free travel.

Germany's Federal Ministry of the Interior suggested that it might be able to help with joint border controls, but the idea was quickly dismissed by Poland's defense minister.

"The minister from Germany will not tell us what to do in Poland," Wladyslaw Kosiniak-Kamysz told broadcaster TVN24. "With sympathy, with respect, but we will protect Polish borders ourselves."

Germany reintroduced controls on its frontier with Poland in late 2023, and in the federal election earlier this year, immigration emerged as one of the most important topics, with the far-right anti-immigrant Alternative for Germany party finishing with the second-highest vote share, behind the mainstream conservative Christian Democratic Union-Christian Social Union alliance, known as the CDU-CSU.

The CDU-CSU's candidate for chancellor, Friedrich Merz, became the country's new leader, and has made immigration control a policy priority, with so-called pushbacks of unsuccessful applicants leading to a significant fall in refugee numbers in Germany. But Tusk said Germany's unilateral approach meant Poland's "patient position" over the issue "is wearing out".

Meanwhile, Poland's Interior Minister Tomasz Siemoniak has called on people who want to support national security to join the official border force, rather than become involved with vigilante groups.

"The Border Guard is waiting," he said. "We have 1,500 new positions. Anyone who meets the criteria is absolutely welcome. But those who insult police officers or try to provoke incidents – this is something we strongly condemn.

"Where the law is broken, the appropriate authorities will respond … (vigilantes) are not supporting our services; they are creating disturbances on the border."

However, Poland's newly-elected President Karol Nawrocki, of the right-wing Law and Justice Party, has spoken in support of "citizen-led control of the borders", and blamed Tusk for confrontations between official and unofficial border patrol groups.