Poland is set to introduce border controls with Germany and Lithuania on Monday, in response to growing criticism of Berlin's decision to push thousands of migrants, who it claimed had crossed the border illegally, back to Poland.
The Polish Government Security Centre (RCB) issued an alert on the issue, announcing "controls at the border with Germany and Lithuania are being introduced from 7 July".
Prime Minister Donald Tusk announced the decision on Tuesday of last week during a cabinet meeting.
"We have taken the decision that we are re-establishing temporary control at the Polish border with Germany and the Polish border with Lithuania," Tusk said.
As Poland, Germany and Lithuania are part of the Schengen area, border controls between them can only be carried out in exceptional circumstances. Typically, there is a free movement policy allowing people to cross borders within the zone.
However, Schengen countries may introduce border controls in situations they consider to be "emergency" or as a "last resort" in response to security threats, such as those that occurred during the COVID-19 pandemic.
Such measures are intended to be temporary, but in practice, they can be renewed several times.
Since 2023, Germany has had controls at its borders with Poland and the Czech Republic in response to illegal migration. Last year, they extended these controls to all their borders.
German Chancellor Friedrich Merz has already spoken of the possibility of Poland introducing border checks during a press conference with Luxembourg Prime Minister Luc Frieden on Tuesday.
"Of course we want to preserve the Schengen area, but freedom of movement within it will only work in the long run if it is not exploited by those who promote illegal migration, and especially by migrant smugglers," he said.
Poland has also announced that it will implement controls with Lithuania in response to migrants entering the country from Belarus and neighbouring Baltic states.
Lithuania responded to the situation by calling for closer cooperation between the two countries, but stressed that it would not implement its own controls along its shared border with Poland.
Lithuania's Foreign Minister Kęstutis Budrys said on Saturday that the country "has no plans to reintroduce border controls".
"Nevertheless, our ... officers not only of the border guards but also of the police, will cooperate closely," he added.
Despite doubts about the compatibility of the measures with the Schengen guidelines, Polish Interior and Administration Minister Tomasz Siemoniak confirmed that the measures would be implemented.
"On the night of Sunday to Monday, we are introducing border controls at these borders. This is taking place in accordance with EU regulations and the Schengen Borders Code," Siemoniak said while in Budzisko on the Polish-Lithuanian border.
"The reason for this decision is a common problem that we have as Lithuania, Poland, the European Union, that is the fight against illegal migration," he added.
Siemoniak also stressed that he could revoke the decision "if Germany lifts its controls".
In Lithuania, controls will be carried out at 13 places, including three border crossings. The remaining 10 border crossing sites will be "ad hoc control sites", which can be used by local residents.
In Germany, border controls will be carried out at 52 locations.
