The explosion that hit Poland on Tuesday night was "likely caused" by a Ukrainian air defense missile fired to intercept an incoming Russian missile, NATO secretary-general Jens Stoltenberg said on Wednesday, though the "ultimate responsibility" falls on Moscow, he claimed.

"Our preliminary analysis suggests that the incident was likely caused by a Ukrainian air defense missile fired to defend Ukrainian territory against Russian cruise missile attacks," the NATO chief told reporters after an emergency meeting of the alliance's Security Council.

Read next: Media reports note that missile that hit Poland was fired by Ukraine

The investigation into the explosion is still ongoing, he said, noting that there was "no indication that this was the result of a deliberate attack. And we have no indication that Russia is preparing offensive military actions against NATO."

"But let me be clear. This is not Ukraine's fault. Russia bears ultimate responsibility, as it continues its illegal war against Ukraine," he claimed.

#NATO ambassadors met to address yesterday’s deadly explosion in #Poland. Allies expressed strong solidarity with our valued Ally Poland, and made clear that we will continue to support #Ukraine’s right to self-defence. We remain vigilant, calm & closely coordinated. pic.twitter.com/7LWd73xu6i

— Jens Stoltenberg (@jensstoltenberg) November 16, 2022

Amid reports about 2 missiles that fell in the village of Przewodów in the Lubelskie Voivodeship near the border with Ukraine, Warsaw called for an emergency national security council meeting.

The Pentagon said it was unable to verify reports that 2 Russian missiles hit Poland soils, but it is investigating the claims. 

"We are aware of the press reports alleging that two Russian missiles have struck a location inside Poland or the Ukraine border," said Pentagon spokesman Pat Ryder.

Meanwhile, in the wake of the unconfirmed reports, Ukraine called for NATO members to convene an "immediate" summit to bring tough measures against Moscow.

"A collective response to Russian actions must be tough and principled. Among immediate actions: a NATO summit with Ukraine's participation to craft further joint actions, which will force Russia to change its course on escalation, providing Ukraine with modern aircraft," Foreign Minister Dmytro Kuleba said on Twitter.

NATO chief Jens Stoltenberg said Tuesday it was important to find out the facts about what caused a deadly explosion in Poland after holding talks with President Andrzej Duda. 

The whole debacle prompted Warsaw to put some of its military units in a heightened state of readiness.

Due to uncertainty regarding the party that fired the missile, Poland suggested invoking NATO's Article 4, which means that the alliance's members "consult together whenever, in the opinion of any of them, the territorial integrity, political independence or security of any of the Parties is threatened."

Stoltenberg, however, underlined that "there has been no call for an Article 4 meeting".

Meanwhile, the Russian Defense Ministry said Tuesday that Poland's statements about "Russian missiles" are a deliberate provocation to try and escalate the situation.

"Statements by the Polish media and officials about the alleged fall of 'Russian' missiles in the area of the settlement of Przewodow is a deliberate provocation in order to escalate the situation. No strikes were made against targets near the Ukrainian-Polish state border by Russian weapons," the ministry said.

They added that "the fragments published in hot pursuit by the Polish media from the scene in the village of Przewodow have nothing to do with Russian weapons."

Macron calls for G20 talks over Poland situation

French President Emmanuel Macron called late Tuesday for talks over the reports alleging that Russian missiles landed in Poland to be held at the G20 summit currently underway in Indonesia, the Elysee Palace told the press.

Efforts were underway to "explore the possibility of a discussion tomorrow morning at the level of leaders... given the presence of all our major European partners and our major allied partners at the G20" summit, attended by Macron, the French presidency said, as quoted by AFP.

This comes after reports said Macron would call his Russian counterpart, Vladimir Putin, after the G20 summit, where Russia is expected to face intense pressure.

A senior Elysee official told journalists that Macron "will call him after the G20," lamenting Putin's "isolation" over the war in Ukraine.

Unlike other European leaders, the French President has kept in contact with Putin and will "continue to talk," as per the official.