Polish Prime Minister Donald Tusk has denounced as "unacceptable" Germany's decision to extend temporary controls to all its land borders as part of its response to irregular migration.

He is one of several figures from neighbouring countries to criticise the move. Restrictions already in place at some of Germany's land borders will apply from next Monday with France, Belgium, the Netherlands, Luxembourg and Denmark.

The head of a Dutch-German alliance of border communities said it was a "panic reaction", while Austria's interior minister stressed it would not be take in anyone turned away by Germany.

However, Germany's opposition conservatives said Berlin had not gone far enough.

The three-parties in Chancellor Olaf Scholz's government have come under increasing pressure to respond to poor results in state elections in eastern Germany where immigration was the biggest issue.

In Thuringia, the far-right Alternative for Germany came first, and another election is on the horizon in less than two weeks in Brandenburg.

The migration debate has been ignited by the killing of three people at a festival in Solingen in western Germany where a Syrian failed asylum seeker who should have been deported was arrested.

The conservative CDU/CSU parties said initially they would take part in a migration summit of the government and state leaders on Tuesday, aimed at reaching an agreement on the next steps.

But they pulled out, accusing the government of not taking seriously conservative proposals to reject asylum seekers at the border.

"Clearly the federal government is hopelessly divided internally and cannot agree on effective measures," said CDU leader Friedrich Merz.

Germany and all its neighbours are part of the Schengen border-free zone and under European Union rules temporary controls are allowed "as a last resort measure, in exceptional situations" for up to six months .