Russian spies tried to spike hundreds of artillery shells with rocks and stones so they would blow up in troops’ faces.

Covert GRU operatives penetrated supply lines from eastern Europe to Kyiv’s military weeks ago in a bid to upset the war effort and kill or maim soldiers. They were able to nobble the badly-needed shells before they were transported to ’s frontlines, hoping to undermine Kyiv’s war-effort.

But Ukraine’s uncovered the plot and urgently inspected entire batches of dud 122mm artillery shells used in Soviet-era D-30 Howitzer guns. It is the latest effort by Moscow’s undercover military intelligence spies to try and undermine Kyiv’s battle against the Russian full-scale invasion.

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And there are even fears among British military experts that could try to sneak into the UK military procurement process to launch a similar operation. In leaked documents obtained by the MIrror and sent to Ukraine’s military command photographic evidence shows how the shells were filled with rocks and grit.

Some of the spiked shells are believed to have been fired and blew up just metres away from weapons from which they were unleashed. A sinister video of the evidence sent on to the Ukraine MoD by investigators shows a spiked shell, with a concerned voice telling the reader in the Ukraine defence ministry.

“Look, here is the gunpowder mixed with rocks and stone. That’s sabotage. They have dismantled the cartridge and found stones mixed with gunpowder which causes the cartridge to be ripped apart on ignition. Without stones it would propel the warhead but the stones cause a premature explosion in soldiers’ faces.”

Former commander of British forces in and adviser to the UK government on terrorism Colonel Richard Kemp told the : “It does not surprise me at all that Russia has tried espionage and sabotage to interfere with the supply process of weapons to Ukraine. They will do this by trying to recruit agents to damage, discredit and spike weapons being supplied to Ukraine to undermine confidence and cause actual harm. They will do anything to undermine the war effort and I have no doubt they would try to do this to the UK military’s supply chains.”

It is believed Moscow has resorted to trying to meddle with Ukraine’s weapons supply chain because it is struggling to finance its own side of the war. And it has also set up a system of off budget soft loans in which the Kremlin has bullied banks into making easy credits to defence sector companies in a bid to fund the war machine.

But with the soaring cost of borrowing that has become a problem. Ukraine has also suffered issues with receiving sub-standard artillery rounds and frontline troops have complained about a dire shortage of shells to be fired against Russian forces. Eastern European middle-men have also blighted the flow of weapons into Ukraine by over-charging and not processing the supply chain quick enough. And some of the weapons sent to Ukraine from east European countries have been sub-standard or out of date.

Meanwhile, Polish Prime Minister Donald Tusk laid into Moscow over its espionage missions. He accused Russia of planning acts of sabotage worldwide that included "acts of air terror" against airlines. Mr Tusk spoke at a news conference in Warsaw alongside Ukrainian President . The Polish leader said: "I will not go into details, I can only confirm the validity of fears that Russia was planning acts of air terror, not only against Poland, but against airlines around the ."