Seven people have been killed and 11 others injured after a drone hit a passenger bus travelling through a Russia-controlled part of Ukraine, an official said.

Denis Pushilin, the Kremlin-installed leader of Ukraine's eastern Donetsk region, said the bus was struck in the early hours of Wednesday as it was travelling between Moscow and Simferopol, in Russian-occupied Crimea.

Black smoke could also be seen rising over St Petersburg on Wednesday morning, with Ukraine President Volodymyr Zelensky confirming the city's oil terminal had been hit.

The attack comes as the city hosts the annual International Economic Forum, an event designed to showcase Russia to the world.

The strikes come a day after a massive Russian assault on cities across Ukraine killed at least 22 people, including several women and children.

On the drone which hit the bus in Donetsk, Pushilin said: "In Yenakiyevo, a UAV attacked a Moscow-Simferopol coach; according to preliminary reports, seven civilians were killed."

He added the 11 injured people were receiving medical care.

Andriy Kovalenko, the head of the Ukrainian government's centre for combating disinformation, has talked about a "parallel reality" created by Russian state propaganda, while not explicitly denying claims that the strike took place.

"Russia attacks civilians with drones all the time... of course, when everyone is talking about this, when there is evidence of such actions by the Russians, they use their main propaganda tool: creating a parallel reality," he told the BBC.

"Against this background of attacks on our civilians, they come up with stories in which Ukraine acts just like Russia. This is done to justify their own terror as a response to our actions."

The BBC has approached the Ukrainian military for comment.

Drones were downed over Belgorod, Kursk and other western regions, as well as near Moscow and over the Sea of Azov, Russian officials added.

In total, Russia says it shot down 350 Ukrainian drones overnight.

At least 50 of the drones were downed over the Leningrad region northwest of Moscow, according to the regional governor Alexander Drozdenko.

The region includes St Petersburg, which is welcoming delegates from around the world for the economic forum from Wednesday.

Russian President Vladimir Putin is expected to address attendees on Friday.

"Important facilities on Russian territory were hit last night," Zelensky wrote on X, sharing a video of black smoke rising above St Petersburg.

He described the strikes as "long-range sanctions" and said Ukrainian forces also hit military targets in Russia's Tambov region.

These overnight strikes saw Pulkovo airport temporarily restrict flights, according to Russian aviation watchdog Rosaviatsia.

Meanwhile, an 86-year-old woman was killed following a drone attack in Ukraine's southern Kherson region overnight, Yaroslav Shanko, head of the city's military administration said.

This came as part of a wider attack by Moscow overnight, with Ukraine's air force saying Russia launched 198 drones at several different regions, 189 of which were shot down.

The latest wave of strikes comes a day after Russia launched one of its largest attacks on Ukraine since its full-scale invasion began in 2022.

At least 22 people were killed after Russia launched more than 700 missiles and drones overnight into Tuesday, Ukrainian officials said.

Russia's defence ministry said the strikes had been a response to previous Ukrainian attacks, saying in a statement that the "strike objectives" had all been achieved.

The Kremlin said on Tuesday it was carrying out the "systematic strikes" it had pledged after accusing Kyiv of a deadly attack on a student dormitory in an occupied part of eastern Ukraine in late May.

Kyiv said it had hit a Russian military unit.

"This practice will continue," Kremlin spokesman Dmitry Peskov told reporters on Tuesday, claiming the strikes were targeting Ukrainian military infrastructure.