MOSCOW — Russia vowed today to “intensify” its strikes on Kyiv in response to Ukrainian drone attacks on Moscow, as an exit poll showed the ruling United Russia party on course to win tightly controlled parliamentary elections.

Ukraine fired waves of drones at Moscow and the surrounding region on the final day of voting, killing two people and setting an oil refinery ablaze, officials said.

Russia’s defence ministry accused Ukraine of attempting to “disrupt the democratic will of Russian citizens” and vowed a response.

An exit poll published by a state-run pollster showed United Russia on course to win 49.4 percent of the vote, around the same it achieved in the previous election.

“In response to the Kyiv regime’s attacks on civilian targets within Russia, the Russian army will continue and intensify its high-accuracy strikes against military targets in Kyiv,” the Russian defence ministry said.

The attack was the largest on Moscow since the Kremlin launched its Ukraine offensive in 2022 and involved some 1,600 drones, 450 of which were aimed directly at the capital, Moscow Mayor Sergei Sobyanin said.

Images showed a gaping hole in a multi-storey apartment building on the outskirts of the capital, while another showed black smoke pouring from what appeared to be an oil refinery.