Nevertheless, NATO’s chief said that Russia, not Ukraine, was still to blame for starting the war in the first place with its February invasion and launching scores of missiles on Tuesday that triggered Ukrainian defences.

“This is not Ukraine’s fault. Russia bears ultimate responsibility as it continues its illegal war against Ukraine,” NATO Secretary-General Jens Stoltenberg told reporters in Brussels on Wednesday.

NATO ambassadors held emergency talks to respond to Tuesday’s blast that killed two people at a grain facility in Przewodow near the Ukrainian border, the war’s first deadly extension into the territory of the Western alliance.

“From the information that we and our allies have, it was an S-300 rocket made in the Soviet Union, an old rocket and there is no evidence that it was launched by the Russian side,” Polish President Andrzej Duda said. “It is highly probable that it was fired by Ukrainian anti-aircraft defence.”

Stoltenberg also said it was likely to have been a Ukrainian air defence missile. Earlier, US President Joe Biden had said the trajectories suggested the missile was unlikely to have been unleashed from Russia.

Ukrainian President Volodymyr Zelenskiy demurred in a nightly video address, saying “I have no doubt that it was not our missile”, Ukrainian media reported on Wednesday. He said he based his conclusion on reports from Ukraine’s military that he “cannot but trust”.

Asked about the discrepancy in accounts from Ukraine, Poland and NATO, a State Department spokesperson in Washington said: “We are aware of President Zelenskiy’s comments … but we do not have any information that would contradict Poland’s preliminary findings.”

The incident occurred while Russia was firing scores of missiles at cities across Ukraine, targeting its energy grid and worsening power blackouts for millions, in what Kyiv says was the most intense volley of such strikes of the nine-month war.

Kyiv says it shot down most of the incoming Russian missiles. Ukraine’s Volyn region, just across the border from Poland, was one of the many Ukraine says was targeted by Russia’s countrywide fusillade.

The Russian defence ministry said none of its missiles had struck closer than 35 kilometres from the Polish border, and photos of the wreckage in Poland showed elements of a Ukrainian S-300 air defence missile. Poland has said it was probably an old S-300 rocket, a Soviet-era missile system being used by both Russia and Ukraine.

The Kremlin said some countries had made “baseless statements” about the incident after having accused Poland of an “absolutely hysterical” reaction, but that Washington had been comparatively restrained.

Zelenskiy also said Kyiv had received no offer from Moscow to start peace talks, and top adviser Mykhailo Podoloyak dismissed the notion of talks.

Some Western leaders at the G20 summit in Indonesia suggested that whoever fired the missile, Russia and President Vladimir Putin would ultimately be held responsible for an incident arising from its invasion.

G20 leaders issued a closing declaration saying “most members strongly condemned the war in Ukraine”, although it acknowledged that “there were other views”.

Moscow carried out Tuesday’s missile volley just days after abandoning the southern city of Kherson, the only regional capital it had captured since the invasion.

The barrage echoed a pattern of Moscow lashing out with longer-range missile salvos after losses on the battlefield to a continuing Ukrainian counteroffensive in the east and south.

However, the top US general played down the chances of any near-term, outright military victory by Ukraine, cautioning that Russia still had significant combat power inside Ukraine despite a string of setbacks.

“Politically, there may be a political solution where, politically, the Russians withdraw. That’s possible,” Army General Mark Milley, chairman of the Joint Chiefs of Staff, told reporters.

Russia “right now is on its back”, Milley said.

-AAP