Polish experts have confirmed that the missile that killed two people at a grain facility in southern Poland in November was fired by Ukraine, Rzeczpospolita daily reported, citing sources.

The explosion of the missile in NATO-member Poland fuelled fears that the war in Ukraine could spiral into a wider conflict by triggering the alliance's mutual defence clause, but at the time Warsaw and NATO said that they believed that it was a Ukrainian stray, easing worries about escalation.

Sources with knowledge of the investigation told Rzeczpospolita that Poland had established that the missile that landed in the village of Przewodow was an S 300 5-W-55 air-defence missile fired from Ukrainian territory.

"This rocket has a range of 75 km to 90 km," the newspaper cited a source as saying. "At that time, the Russian positions were in a place from which no Russian missile could reach Przewodow."

Ukraine has denied that one of its missiles had landed in Poland.

Rzeczpospolita reported that the Ukrainian side has not made any material available to Polish investigators.

It quoted Lukasz Lapczynski, spokesman for the Polish prosecutor's office, as saying the prosecutor had received the experts' opinion but was not disclosing its content as it was confidential.

Lapczynski could not immediately be reached for comment and the prosecutor's office did not immediately respond to an emailed request.

(Reporting by Alan Charlish; editing by Miral Fahmy)