A Ukrainian service member prepares shells for a M777 Howitzer at a front line, as Russia's attack on Ukraine continues, in Kharkiv Region, Ukraine July 21, 2022.
A Ukrainian service member prepares shells for a M777 Howitzer at a front line, as Russia's attack on Ukraine continues, in Kharkiv Region, Ukraine July 21, 2022. Reuters / GLEB GARANICH

Moscow said dozens of Ukrainian prisoners of war had been killed in a missile attack on Friday, a fraught backdrop to U.N.-backed efforts to restart grain shipments from Ukraine and supply parts of the world threatened with starvation.

Russia's defence ministry said 40 prisoners were killed and 75 wounded in the attack on a prison held in separatist-held territory. It accused Kyiv of targeting it with U.S.-made HIMARS rockets, Russian news agencies reported.

There was no immediate official Ukrainian reaction although Petro Andryushchenko, aide to the mayor of the southeastern town of Mariupol, said it was "a lie".

The Russian defence ministry said the prison near the frontline town of Olenivka in Donetsk province housed Ukrainian prisoners of war, and that eight prison staff were also wounded.

Russian-backed separatist leader Denis Pushilin was quoted as saying that the prison housed 193 people and that there were no foreigners among the detainees.

For its part, Ukraine said at least five people had been killed and seven wounded in a Russian missile strike on the southeastern Ukrainian city of Mykolaiv as Russia fired across frontlines in eastern and southern Ukraine.

A missile had struck near a public transport stop, regional governor Vitaly Kim said on Telegram.

Russia, which denies targeting civilians, did not immediately comment on the situation and Reuters could not verify the battlefield reports.

GRAIN HOPES

Russia and Ukraine agreed last week to unblock grain exports from Black Sea ports, which have been threatened by Russian attacks since it invaded Ukraine on Feb. 24.

The deal was the first diplomatic breakthrough of the conflict and wheat prices being offered in Asia slid this week on expectations of higher supplies.

But fierce fighting makes it extremely risky.

United Nations aid chief Martin Griffiths said on Thursday evening he hoped the first grain would move on Friday but that crucial details for the safe passage of vessels were still being worked out.

He emphasised that the operation was commercial - not humanitarian - but he said the United Nations hoped poorer countries would get priority, citing Somalia, where nearly a quarter of a million people face starvation.

While the blockage of grain in Ukraine, one of world's biggest exporters, has fed into food price rises around the world, shortages of Russian gas have raised energy prices in Europe and prompted fears of shortages over winter.

Russian gas flows via the Nord Stream 1 pipeline to Germany remained at just 20% of capacity on Friday, after Russia halved the flows on Wednesday citing maintenance work.

Moscow, which describes its invasion of Ukraine as a "special military operation" conducted in self-defence, blames Western sanctions for the low gas supplies. Ukraine and its allies say the Russian assault was entirely unprovoked.

FOCUS ON SOUTH

An intelligence update from Britain said Russia has ordered mercenaries to hold sections of the frontline in Ukraine - a sign it is running short of combat infantry as Kyiv steps up a counter-offensive in the south.

Greater reliance on fighters from the Russian private military company Wagner Group for frontline duties rather than their usual work in special operations would be another sign that Russia's military is under stress six months into its war in Ukraine.

But the British defence ministry said in the update that Wagner mercenaries were unlikely to make up for the loss of regular infantry units or alter the trajectory of Russia's invasion.

"This is a significant change from the previous employment of the group since 2015, when it typically undertook missions distinct from overt, large-scale regular Russian military activity," the ministry said.

Wagner and the Kremlin were not immediately available for comment.

Officials in Kyiv said on Wednesday they had observed a "massive redeployment" of Russian forces to the south where British defence officials believe Russia's 49th Army, stationed on the west bank of the Dnipro River, is vulnerable.

Ukraine's counter-attacks in the south come as Russia battles for control of the entirety of the industrialised Donbas region in the east, comprising the provinces of Donetsk and Luhansk.