Two people have been killed on NATO territory after Russian missiles crossed into Poland, according to a senior US intelligence official.
An urgent meeting to discuss national security has been called by Polish Prime Minister Mateusz Morawiekci following the strike.
Latvia’s deputy prime minister, Artis Pabriks, indicated that Moscow fired missiles that landed in Poland.
The US Pentagon stated it could not confirm that Russian missiles had crossed into Poland.
A spokesperson for the UK Foreign Office said it is investigating the reports and is liaising closely with allies.
Russian airstrikes targeting energy facilities earlier rocked Ukraine.
A senior official warned that the situation was “critical” as neighbourhoods went dark.
The aerial assault resulted in at least one death in a residential building in Kyiv.
A Ukrainian air force spokesman said Russia fired around 100 missiles.
The country’s President Volodymyr Zelensky put the number at 85.