Poland's defence minister has asked Germany to ship a Patriot surface-to-air missile defence system intended for Poland to Ukraine instead to help defend itself against Russia.

The offer follows a deadly missile blast in a Polish village last week that Warsaw believes may have been a stray Ukrainian air defence missile launched against a barrage of Russian strikes.

"I have asked Germany to send the Patriot system offered to Poland to Ukraine where it could be installed on their western border," Mariusz Blaszczak said on Twitter late on Wednesday.

"This would allow Ukraine to protect itself against incurring more casualties and blackouts and reinforce the security of our eastern border," he said.

The German government earlier this week said it had reached an agreement to help Poland protect its skies following an explosion near the Ukrainian border which killed two people.

Poland and NATO have said the blast was probably caused by a stray Ukrainian air defence missile launched against a Russian strike but have said Moscow is ultimately responsible.

Germany has already sent Patriot air defence units to Slovakia, where Berlin hopes to keep them deployed until at least the end of 2023.