Without naming Germany itself, Morawiecki criticised alliance members that spend less on defence than the targeted two percent of GDP repeatedly insisted upon by US President Donald Trump.

A country that benefits from NATO's collective defence but spends just one percent of GDP, Morawiecki told Germany's Die Welt daily, is "a free rider which threatens the unity of the West".

Germany's military spending amounts to 1.2 percent of gross domestic product.

Morawiecki also charged that "Europe isn't taking defence seriously and living under the umbrella of Pax Americana," according to the German-language article.

"But for Europe, too, the saying goes: If you want peace, prepare for war."

He also voiced disbelief that many Germans trust Russian President Vladimir Putin more than Trump, exclaiming that it made him think "run while you can! It's an upside down world."

Poland has sparred with Germany and the European Union over a range of issues, including its refusal to take in an EU quota of refugees, and controversial judicial reforms.

German Chancellor Angela Merkel days ago welcomed Morawiecki's upcoming visit as a chance to open "a new chapter" in relations despite "divergent views on some issues".

However, Morawiecki pointed to other areas of friction, including plans for a Russia-Germany gas pipeline called NordStream 2 that would run through the Baltic Sea and bypass Poland.

He argued that if the new pipeline replaced one now carrying Russian gas through Ukraine, then Russia could "escalate the conflict with Ukraine, attack all of Ukraine".

The Polish prime minister also defended a controversial Holocaust bill that would penalise statements attributing Nazi crimes to the Polish state, notably by referring to "Polish death camps".

Poland, which had lost half a century to war and communism, had long been treated as a "whipping boy", he said, adding that it must now be able to "tell the truth about this time".