Ukrainian drone attacks on Russia sparked a brief fire at an oil refinery, targeted Moscow and disrupted electricity in border areas, Russian officials said early on Sunday, the final day of the country's presidential vote.
Putin, all but certain to win re-election, has vowed to punish Ukraine for the attacks.
Ukraine's President Volodymyr Zelenskiy thanked his military forces and intelligence for new "long-range capabilities" in his nightly video address on Saturday, without mentioning the reported intensified attacks by his nation's forces.
Reuters could not independently verify the reports.
"The drones were neutralised, but a fire broke out as a result of the fall of one of the devices," the operational headquarters of the Krasnodar region in southern Russia said on the Telegram messaging app on Sunday.
The fire at the Slavyansk refinery in Krasnodar was extinguished and there were no casualties as a result of the fire, although preliminary information indicated one person had died of a heart attack, the administration said.
Roman Siniagovskyi, head of the Slavyansk administrative district, said on Telegram refinery workers were evacuated and there was no threat to nearby populated areas from the incident.
Russia's air defence systems destroyed four drones flying towards the capital, said Moscow Mayor Sergei Sobyanin. No casualties or damage were reported from the incidents that affected three districts near Moscow.
North of Moscow four drones were destroyed over the Yaroslavl region, with no damage or injuries reported, Governor Mikhail Yevrayev said on Telegram.
In the border region of Belgorod, an attack by four Ukraine-launched drones damaged electricity and gas lines in one village, said Governor Vyacheslav Gladkov.
