Ukrainian forces have struck one of Russia's "most important military factories", President Volodymyr Zelensky has said.

"The plant produced electronics and components for Russian missiles. The very missiles that strike our cities, our villages and civilians," he said.

British Storm Shadow missiles were used to hit Kremniy El plant in the border region of Bryansk, Ukraine's military said.

Russian local authorities say at least six civilians were killed and 42 injured in the "terrorist missile attack". President Vladimir Putin's spokesman said it was "obvious that the launch of these missiles was impossible without British specialists".

"In order to prevent such barbaric actions by the Kyiv regime from continuing, the special military operation is being conducted," Dmitry Peskov said, using the Russian description for the full-scale invasion of Ukraine that Putin ordered on 24 February 2022.

Peskov said one of the goals of the Russian operation was to demilitarise Ukraine. Putin himself has often stated that demilitarisation is a central objective of the war.

But it is due to the Russian invasion that Ukraine has been receiving Western support - including sophisticated weapons aimed at defending its territories.

Russia, for its part, has also been receiving help from its allies, including Shahed drones supplied by Iran and soldiers sent by North Korea.

One of those drones was used in an attack which killed two people and injured another five in the second-largest city of Kharkiv on Wednesday, Ukrainian officials said.

Another Russian attack a day earlier in Slovyansk, in eastern Ukraine, killed four and injured 16.

Both sides have continued attacks, even though the war has reached a stalemate recently.

Russia has been making slow advances in the battlefield, but Ukraine also says it is reclaiming more land seized by the Russians.

Zelensky says another round of talks - involving Russian and American negotiators - may be held next week.

The process is being led by US President Donald Trump, who has been trying to end the war.

The outcome of the talks hinges on part of his proposals that envisages Ukraine giving up to Russia areas it does not currently control in the Donbas - an industrial area composed of the administrative regions of Donetsk and Luhansk.

Russia currently controls more than 80% of those areas - which Ukraine says it cannot agree to relinquish.