NATO secretary-general Jens Stoltenberg said today that a missile strike in Poland was not “the result of a deliberate attack” by Russia.

Mr Stoltenberg said a deadly blast that killed two people was likely caused by a Ukrainian air defence missile fired in response to a Russian attack.

He said: “This is not Ukraine’s fault. Russia bears ultimate responsibility as it continues its illegal war against Ukraine.”

The two victims were killed on Tuesday when a missile came down in Polish farmland not far from the border with Ukraine. 

The blast came amid a Russian aerial assault in Ukraine and raised fears that the war could expand beyond its borders and spark a direct Nato-Russia war, as Poland is a member of the alliance.

Mr Stoltenberg said that neither Poland nor any other ally had called for emergency consultations under article 4 of Nato’s founding treaty, which provides for such talks if any of the allies consider that their territory might be under threat.

After initially stating they were considering invoking article 4, Polish President Andrzej Duda said: “Ukraine’s defence was launching its missiles in various directions and it is highly probable that one of these missiles unfortunately fell on Polish territory.

“There is nothing, absolutely nothing, to suggest that it was an intentional attack on Poland,” he said.

But even after it was accepted that the missile had not been fired by the Russians, Ukrainian President Volodymyr Zelensky continued to claim it was a Russian attack on Nato.

He said: “Terror is not limited to our national borders. Russian missiles hit Poland. To fire missiles at Nato territory is a Russian missile attack on collective security! This is a very significant escalation. We must act.”

The remarks by Mr Zelensky have prompted speculation that the strike could have been a deliberate attempt by Ukraine to provoke full-scale involvement by Nato forces.

US Black Alliance for Peace organiser Ajamu Baraka said: “The comments by the actor-president of Ukraine on the missile strike in Poland demonstrated once again why his reckless and immature leadership poses a threat to global security.”

Code Pink co-founder Medea Benjamin said: “We have been warning for months that an errant missile strike on a Nato country could lead to a direct Russia-Nato confrontation. 

“All the more reason to push for all sides to sit down at the table for peace talks.”