A missile has killed two people in the Polish village of Przewodow near the border with Ukraine, which has come under heavy Russian bombardment.

Here is a summary of what we know about Tuesday's incident:

What happened?

Two men aged about 60 were killed when a missile hit the southeastern Polish village of Przewodow, some six kilometres (four miles) from the Ukrainian border, on Tuesday afternoon.

The foreign ministry said the missile blast occurred at 1440 GMT on Tuesday. Residents said it hit a local grain drying facility, near a school.

Police tape preventing access to the area of the explosion in the village of Przewodow, Lublin Voivodeship, on November 16, 2022 in Przewodow, Poland

The explosion occurred as Russia targeted Ukraine with a massive attack on civilian infrastructure Tuesday which left millions of households without power.

Russian missiles hit cities across Ukraine, including Lviv near the Polish border.

Who fired the missile?

Russia, which invaded Ukraine in February, immediately came under suspicion.

But Polish President Andrzej Duda said Wednesday it was "very likely" that the missile was fired by Ukraine defending itself from Russian missiles.

Aerial weapons expert Pierre Grasser from the Paris-based Sirice research institute identified the missile type as 5V55, which is used by the Ukrainian army.

"The blast was most probably an accident involving a Ukrainian surface-to-air missile which missed its target or got out of control," Grasser told AFP.

He added NATO systems would most probably have noticed a similar missile fired from nearby Belarus, which is Russia's ally.

What are the consequences?

The explosion sparked concerns that NATO, which Poland joined in 1999, might be drawn into the conflict between Russia and Ukraine.

Poland is protected by NATO's commitment to collective defence -- enshrined in Article 5 of its founding treaty -- but the alliance is unlikely to invoke it given the likely origin of the missile.

Poland put its military on heightened alert following the blast. It also summoned the Russian ambassador for "immediate detailed explanations".

Who said what

Kyiv, which blamed Russia for the blast, demanded "immediate access to the site of the explosion".

A line of military vehicles near the access to the area of the explosion in the village of Przewodow

Oleksiy Danilov, the secretary of Ukraine's national security and defence council, said Ukrainian officials wanted to take part in "a joint examination of the incident" on the site.

He added that Kyiv was ready to hand over "evidence" of its allegations that Russia was responsible.

Russia has denied any wrongdoing, calling the incident "a provocation" and insisting that it had "nothing to do with the missile blast".

Western leaders held an "emergency roundtable" on the fringes of the G20 summit on Wednesday, expressing solidarity with Poland and urging caution as to the origin of the missile.

NATO chief Jens Stoltenberg said Wednesday there was "no indication that this was the result of a deliberate attack", saying the blast was likely caused by a Ukrainian missile.

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