Parts of south-west Russia and Crimea, which is under Russian control, have experienced loud explosions during the night.
According to Russian authorities, the border city of Belgorod, where 25 people died on Saturday, was attacked again, along with Sevastopol in Crimea, where a Ukrainian missile was intercepted.
The aerial conflict between Russia and Ukraine has escalated in the past few days.
Ukrainian President Volodymyr Zelensky says Russia deployed some 300 missiles and 200 drones over five days.
Russia carried out its largest air raid of the invasion at the end of last week, killing more than 40 people. Ukrainian forces retaliated with the assault on Belgorod, which also wounded more than 100 people.
More explosions were heard in Belgorod on Wednesday night, with the regional governor saying several drones had been shot down.
In Sevastopol – the biggest city in Crimea, which Russia seized in 2014 – a missile was brought down over the harbour, the governor appointed by Moscow, Mikhail Razvozhayev, said on Telegram. There were no reports of injuries or damage.
On Tuesday, Russian missiles struck Ukraine’s major cities including Kharkiv and Kyiv, killing at least five people and injuring many others, local officials said. One person was also said to have died in a Ukrainian attack on Belgorod.
Those attacks followed Russian President Vladimir Putin’s pledge to increase strikes in response to recent attacks by Ukraine.
In his evening speech on Tuesday, Mr Zelensky said Russia had launched “almost one hundred missiles of various kinds” that day. They were, he said, “deliberately designed by the enemy to inflict as much harm as possible”.
Later, speaking to the BBC, the Ukrainian ambassador to the US, Oksana Markarova, said Russia’s recent bombardment was “not something that was unexpected” – but that Ukraine needed more weapons to fight back and “just clearly tell Russia that they should stop”.
