Germany on Tuesday urged the European Union to "take action" and help stem the flow of migrants illegally crossing into Poland from Belarus.
"Poland or Germany can't handle this alone," caretaker Interior Minister Horst Seehofer told the Bild daily, urging the EU to "stand together".
"We must help the Polish government secure their external border. This would actually be the task of the European Commission. I'm now appealing to them to take action," he said.
The plea came after Poland said it had repelled an attempt by hundreds of migrants to illegally cross from Belarus.
Warsaw warned that thousands more were on the way and future attempts to breach its frontier could be "armed in nature".
AFP quoted Seehofer as saying that he supported Poland's decision to build a border wall.
"We cannot criticize them... for protecting the EU's external borders," Seehofer told Bild. "Not through the use of firearms of course, but with other means that are available."
The EU accuses Belarusian President Alexander Lukashenko of flying migrants from the Middle East and Africa to Minsk and then sending them into the bloc on foot in retaliation for sanctions imposed by Brussels over his regime's crackdown on the opposition.
Lukashenko denies the accusation.
European Commission President Ursula von der Leyen on Monday called on member states to impose new sanctions against Belarus over the migrant flows.
The use "of migrants for political purposes is unacceptable", she said, adding that the EU would also look at how to sanction "third-country airlines" flying migrants to Belarus.
As Poland's neighbor, Germany has seen a steep rise in migrants entering from Belarus via Poland.
In October alone, the number stood at nearly 5,000, according to German authorities.
Berlin has responded by stepping up border controls and deploying extra police officers.
Germany stands ready to offer police support to Poland, said Stephan Mayer, parliamentary state secretary in Germany's interior ministry.
"Germany could very quickly send police forces to assist Poland, if Poland so wishes," Mayer told the Bild newspaper.