US President Joe Biden says the missile that killed two people in Poland was “unlikely” to have been fired from Russia.

Mr Biden spoke to the media on Wednesday afternoon, after an emergency meeting with global leaders gathered for the G20 meeting in Bali held an emergency meeting on Wednesday following deadly explosions in Poland that Ukraine and Polish authorities said were caused by Russian-made missiles.

Mr Biden said the group would support Poland’s investigation into the incident.

“I’m going to make sure we figure out exactly what happened … Then we’re going to figure out our next step,” he said.

The US and its NATO allies are investigating the deadly blast. But early information suggested it might not have been caused by a missile fired from Russia, Mr Biden said.

“There is preliminary information that contests that. I don’t want to say that until we completely investigate it but it is unlikely in the lines of the trajectory that it was fired from Russia but we’ll see,” he said.

The US and NATO countries would fully investigate before acting, he said.

Wednesday’s emergency G7 meeting was convened by Mr Biden, the White House said, after two people were killed in an explosion in Przewodow, a village in eastern Poland near the border with Ukraine.

The Polish foreign ministry said the rocket fell at 3.40pm Tuesday (local time). A resident who declined to be identified said the two victims were men who were near the weighing area of a grain facility.

“We agreed to support Poland’s investigation into the explosion in rural Poland, near the Ukrainian border, and they’re going to make sure we figure out exactly what happened,” Mr Biden said.

“And then we’re going to collectively determine our next step as we investigate and proceed. There was total unanimity among folks at the table.”

Leaders from the US, Germany, Canada, Netherlands, Japan, Spain, Italy, France and Britain were involved in the meeting.

All except for Japan are members of NATO, the defence alliance that also includes Poland.

Also in Bali, Australia’s Prime Minister, Anthony Albanese, said the “deeply concerning” attack needed a full investigation.

“Russia’s reckless and dangerous use of force promote danger for the entire region and we have seen that and I send my condolences to Poland on the loss of life,” he told a meeting with European leaders on the G20 summit’s sidelines.

“We need to have a full investigation as to how this has occurred … and we should consider what as an international community is an appropriate response.”

Foreign Minister Penny Wong said she had spoken to Australian ambassador to Poland Lloyd Brodrick and confirmed no Australians were harmed in the blast.

“I understand this is news that is worrying and deeply concerning to Australians … I echo the words of the Polish prime minister, who called on all Poles to remain calm and prudent,” she said in Adelaide.

“We will stay in close contact with our friends and partners.”

Australia is the largest non-NATO provider of support to Ukraine in its defence against the Russian invasion.

A determination that Moscow was to blame for the blast could trigger NATO’s principle of collective defence known as Article 5, in which an attack on one of the Western alliance’s members is deemed an attack on all, starting deliberations on a potential military response.

Poland has said it is verifying whether it needs to request consultations under Article 4 of the alliance, which allows NATO members to bring any issue of concern, especially regarding security, for discussion at the North Atlantic Council.

Poland summoned Russia’s ambassador to Warsaw for an explanation after Moscow denied it was responsible.

Poland was also increasing the readiness of some military units, Polish Prime Minister Mateusz Morawiecki said.

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But Polish officials sought to avoid inflaming the situation. Mr Morawiecki called on all Poles to remain calm and President Andrzej Duda said there was no concrete evidence showing who fired the missile.

He said the government was acting very calmly and it was a one-off incident.

A NATO official said the alliance was closely co-ordinating with Poland.

Mr Biden told Mr Duda in a call that Washington had an “ironclad commitment to NATO” and would support Poland’s investigation, the White House said.

The Associated Press earlier cited a senior US intelligence official as saying the blast was due to Russian missiles having crossed into Poland.

But in Washington, the Pentagon, White House and US State Department said they could not corroborate the report and were working with the Polish government to gather more information.

State Department said the report was “incredibly concerning”.

Ukraine’s President Volodymyr Zelensky said Russian missiles hit Poland in a “significant escalation” of the conflict.

He did not provide evidence.

Russia’s defence ministry denied Russian missiles hit Polish territory, describing reports as “a deliberate provocation aimed at escalating the situation”.

It added in a statement: “No strikes on targets near the Ukrainian-Polish state border were made by Russian means of destruction.”

Kremlin spokesman Dmitry Peskov said he had no information on an explosion in Poland.

Russia pounded cities across Ukraine with missiles on Tuesday, in attacks that Kyiv said were the heaviest wave of missile strikes in nearly nine months of war.

Some hit Lviv, which is less than 80 kilometres from the border with Poland.

-with AAP