VLADIMIR PUTIN suffered a major setback to his military campaign after saboteurs inflicted a devastating blow on Russian supply lines.

The Ukrainian attackers destroyed a railway bridge in the Kursk region close to the border with Ukraine. The incident occurred on the same day as a fire broke out on property belonging to Russia’s Ministry of Defence in the Belgorod region. The railway line where the bridge collapsed runs from the city of Kursk to Sudzha and then continues onto Ukraine towards the city of Sumy.

It is used mainly for the transportation of goods and is a key supply line for the Russians.

Christo Grozev, a Bellingcat investigative journalist, tweeted: “Russia now also admits “saboteurs” blew up a railroad bridge near Kursk.”

The damage to the bridge was initially confirmed by the governor of the Kursk region on his official Telegram channel.

Roman Starovoit said: “Today at approximately 11.20am officials discovered partial damage to the bridge located at the 67 km mark on the rail line between Sudzha and Sosnovy Bor.

“Special services are at the scene and attempting to ascertain the cause of the damage.”

Later in a video, the governor added: “Dear friends, unfortunately, we have now confirmed that the damage to the bridge was caused by an act of sabotage.

“Therefore we have initiated a criminal investigation and we will give you more details in due course.”

Photos of the bridge show substantial as opposed to “partial” damage, eliciting ironic comments from social media users.

One said: “Fortunately, it was only partially destroyed!”

While another wrote: “They can still run a very small train over it so partial works.”

Russian authorities are facing a huge challenge to prevent sabotage attacks against infrastructure targets in the country.

There are many Ukrainians who have lived in Russia well before hostilities broke out in February and who would have every motivation to take up arms against the Kremlin.

According to a 2010 census, 1.9 million people identified themselves as Ukrainians.

This represents 1.4 percent of the total population in Russia. Ukrainians are in effect the third-largest ethnic group after Russians and Tartars.

Dmitry Grozoubinski, an expert on trade and diplomacy, said Russia faced an almost impossible task to secure its key infrastructure from future attacks.

He wrote: “Don’t envy Russian policy-makers trying to deal with this.

“Consider what it would be like to try to protect Russian infrastructure targets from highly motivated creative operators that look like Russians, speak Russian, and in many cases probably have Russian passports.

“Especially as almost anything can be a target.

“Every bridge, rail head, factory, power plant, radio tower, military facility, depot, oil refinery…”

On Sunday, a large fire broke at a facility belonging to the Russian Ministry of Defence in the Belgorod region.

The city of Belgorod, which is the region’s administrative centre, is just 40 km from Ukraine’s border.

The blaze injured one person and damaged seven homes in the locality.

Vyacheslav Gladkov, the region’s governor, said: “A fire has occurred on the territory of one of the facilities belonging to the MoD.

“All operational services are working at the site and all essential measures are being taken to ensure safety. There is information about one injured person among local residents.

“The injury is not serious and there is no danger to life. All necessary medical help is being provided.”