"The Prime Minister spoke to Polish President Andrzej Duda today from the G20 in Indonesia, following reports of a missile strike in Poland," Downing Street said in a statement.

"He reiterated the UK's solidarity."

"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 stay in touch and coordinate with allies, including NATO, "on the next steps", the statement said.

Poland says the missile strike in the village of Przewodow involved a Russian-made munition and has summoned Moscow's ambassador to give "immediate, detailed explanations".