Prime minister Rishi Sunak has offered Poland “any assistance needed” to establish responsbility for a missile strike on its territory.
Mr Sunak, who is attending the G20 summit in Indonesia, spoke by phone with Polish president Andrzej Duda shortly after reports emerged that Russian missiles had landed in the Nato member close to its border with Ukraine.
The prime minister said the UK was co-ordinating with Nato partners and stands ready to support its allies as they seek to establish the facts behind the incident, believed to have killed at least two people.
News of the missile strike cast a shadow over the gathering in Bali of world leaders including US president Joe Biden, Chinese president Xi Jinping and Russian foreign minister Sergei Lavrov.
A White House spokesperson said that in a call with Duda, Mr Biden offered Poland “full US support” in its investigation.
Speaking from the summit, Mr Sunak said he had spoken by phone with foreign secretary James Cleverly and defence secretary Ben Wallace in the wake of the incident.
“We are urgently looking into reports of a missile strike in Poland and will support our allies as they establish what has happened,” said the prime minister.
“We are also coordinating with our international partners, including Nato.”
A Downing Street spokesperson said the PM also spoken by phone with Mr Duda.
“He reiterated the UK’s solidarity with Poland as a close ally and expressed condolences for the victims and their families,” said the spokesperson.
“President Duda updated on the Polish investigation efforts, and the prime minister offered any assistance needed to urgently establish what happened.
“The leaders agreed to remain in close contact and continue coordinating with our international partners, including Nato allies, on the next steps.”
Mr Sunak confronted Mr Lavrov on Tuesday over Russia’s nine-month invasion of Ukraine.
Facing Lavrov across the G20 conference table, the PM said that Russia’s president Vladimir Putin was in a position to reverse the “illegal” invasion and stop the suffering in Ukraine at a stroke.
“One man has the power to change all of this,” said Mr Sunak.
“It is notable that Putin didn’t feel able to join us here. Maybe if he had, we could get on with sorting things out.
“Because the single biggest difference that anyone could make is for Russia to get out of Ukraine and end this barbaric war.”
It was the first time a UK prime minister has gone face-to-face with a representative of the Moscow regime since the start of the invasion in February, and came a day after Mr Sunak described Putin’s Russia as a “pariah state”.
Mr Lavrov has been isolated at the annual gathering of the world’s most influential economies, with other leaders refusing to take part in the traditional family photo with him.
He was forced to watch as Ukrainian president Volodymyr Zelensky addressed the summit by video link, telling world leaders that to liberate his country’s territory, “we will have to fight for a while longer”.
Speaking in Lavrov’s presence, Mr Sunak paid tribute to the “incredible fortitude” of the Ukrainian president and vowed to continue supporting Kyiv “for as long as it takes”.