Poland's prime minister said Saturday he feared a Russian attack on his country, Finland or the Baltic states and urged Europe to double defence spending after Moscow's invasion of Ukraine.

Putin will "want to develop his aggressive policy, his invasion", Mateusz Morawiecki told French daily Ouest-France.

"He started in Georgia, now Ukraine," he added. "The next target could be the Baltic countries, Poland, Finland or other countries on the eastern flank."

Poland, a former Soviet satellite and now a member of the NATO alliance, shares a long border with Ukraine.

As Russian President Vladimir Putin massed forces on his neighbour's frontier before attacking on Thursday, Poland hosted more troops from the US-led military alliance.

But he said Saturday: "We need a strong European army."

The continent must increase defence spending from around 300 billion euros to up to 600 billion euros per year, he argued.

"It is not impossible and that will allow Europe to finally play a major role," Morawiecki said in an interview also published by the German regional media group Funke Mediengruppe.

"The era of peace and international order is coming to an end," he added.

"It is a test for the West and the way we react to this test will determine our future, not for years but decades."

Poland's head of government proposed excluding defence spending from EU public finance rules to allow his country to spend three to four percent of its annual economic output on defence following Russia's aggression.

He also called for an "unprecedented and crushing" sanctions package on Moscow and for discussions to make Europe "independent" of Russian hydrocarbons.

"By buying Russian oil and gas, we are today financing Russia's policy of aggression," he said.

Warsaw has been in the European Union's firing line for defying the supremacy of EU law and amid concerns over the independence of its judiciary.

But Morawiecki said he expected the European Commission "not to bother us with the so-called rule of law procedure... because we are currently defending the eastern flank.

"We are treated in a discriminatory way even in times of war. We should not be treated like that."