The UK on Tuesday announced new sanctions against senior Russian military commanders, as well as Iranians involved in the producing and supplying drones to target Ukraine.
The government said 12 Russian top brass would be subject to assets freezes and travel bans, including Major General Robert Baranov, who is said to be in charge of a unit programming and targeting cruise missiles.
The Foreign Commonwealth and Development Office (FCDO) said more than 6,000 Ukrainian civilians are thought to have been killed since the Russian invasion in February, mainly as a result of missile and artillery strikes.
"Intentionally directing attacks against civilians and civilian objects is a serious violation of international humanitarian law. Those responsible must be held to account," it said.
Iranian-manufactured drones supplied to Russia have played a "central role" in such attacks, the FCDO said.
Foreign Secretary James Cleverly said the Tehran regime, which has been hit by a wave of civilian protests in recent months, was "striking sordid deals" with Moscow "in a desperate attempt to survive".
Last week, the United States voiced concern at what it said was a "full-scale defence partnership" between Russia and Iran, calling it "harmful" to Ukraine, Iran's neighbours and the world.
The latest UK sanctions target four Iranians, include the managing director of the company that manufactures engines for drones used by Russia to attack Ukraine, he added.
On Monday, Cleverly accused Russian President Vladimir Putin of "waging a 19th-century war of imperial conquest" against its neighbour.
"Putin's goal is to turn back the clock to the era when might was right and big countries could treat their neighbours as prey," he added.
