On Saturday, the last day of Russia's international economic forum in St Petersburg, Ukraine's armed forces again shelled the metropolis in what Governor Alexander Beglov and civil defence officials called a "large-scale attack by military drones."
At Pulkovo Airport, which is important for the forum's international guests, there were temporarily no take-offs and landings early in the morning because of the danger.
Air defences were active, the officials said.
On the first day of the economic forum on Wednesday, black clouds of smoke formed in the blue sky above the old town after an attack on an oil refinery. The old town is part of a UNESCO World Heritage site.
"In accordance with the recommendations of the Operational Headquarters, I ask the people of St Petersburg to stay at home and not go out onto the streets," Beglov posted on Telegram. He warned of disruptions to mobile internet services.
Fires and damage in several parts of Russia
In the Leningrad region around St Petersburg, which was known a Leningrad in Soviet times, Governor Alexander Drozdenko also reported a drone alert. Air defences shot down 141 drones, he said.
This led to fires, according to the statement. There were also attacks in the Baltic Sea port of Kronstadt used by the Russian navy, it said.
Reports of drone strikes also came from the Krasnodar region in the south and from other parts of Russia. The port of Mariupol in the Donetsk region annexed by Moscow was also affected, it said.
After explosions, oil depots caught fire, media reported. Social networks circulated videos from independent sources that could initially not be verified showing large fires and plumes of smoke.
Ukraine's drone attacks against Russia's oil industry and military targets were repeatedly a topic at the economic forum. Ukraine is defending itself with these counter-attacks against Russia's war of aggression, which has been going on for more than four years.
Russian President Vladimir Putin acknowledged at the forum on Friday evening that the attacks were causing "some damage" to the economy.
"These attacks naturally do not lead to anything good," he said. Strengthening air defences was important, Putin said, adding that there were no risks to Russia's economy.
He rejected Ukrainian President Volodymyr Zelensky's offer of a meeting for peace talks.
