Russia is suspected of placing an incendiary device on a plane to Britain in a sabotage attack that could have caused the aircraft to crash out of the sky.

British counter-terrorism police are investigating after the parcel containing the device caught fire in a DHL warehouse in Birmingham on July 22.

The Telegraph understands that there are suspicions that Moscow was behind the attack.

The suspect parcel arrived in Birmingham by air, The Guardian reported. If it had ignited while the plane was in flight, the result could have been catastrophic, experts said on Wednesday night.

Russia has stepped up sabotage attacks on European soil in recent months, with Ken McCallum, the head of MI5, warning last week that Vladimir Putin was intent on causing “mayhem” on British and European streets.

He revealed that GRU, Russia’s foreign military intelligence unit, had carried out “arson, sabotage and more dangerous actions conducted with increasing recklessness” in Britain since the Russian invasion of Ukraine.

On Monday, Germany reported a near-identical incident in which an incendiary device caught fire in a DHL facility before it was due to be carried on a plane out of Leipzig.

A Metropolitan Police counter-terrorism spokesman said: “On Monday 22 July, a package at the [Birmingham] location caught alight. It was dealt with by staff and the local fire brigade at the time and there were no reports of any injuries or significant damage caused.”

“Officers are liaising with other European law enforcement partners to identify whether this may or may not be connected to any other similar-type incidents across Europe.”

Incendiary devices are designed to catch fire rather than explode and as such are easier to conceal than simple bombs.

New front in Russia’s hybrid war

The parcel fire in Leipzig also occurred in July, prompting German authorities to write to logistics and transport firms the following month warning that packages containing incendiary devices had caught fire en route across Europe, and that more such parcels could be circulating.

In September, The LoadStar, a logistics industry news site, reported that a package originating from the Baltics had caught fire in Leipzig, one of “several” that caught ablaze in European countries. The packages were said to contain liquids and electronic consumer devices.

The European Commission is investigating the proliferation of attempts to send incendiary devices around Europe.

A Western official told The Telegraph it was seen as a new front in Russia’s hybrid war on Nato countries and had caused a number of mysterious warehouse fires around Europe.

In one of the most common routes, devices originating in Lithuania were sent to Germany, Poland or elsewhere.

One source said these incendiary devices don’t get caught by the security controls carried out by air freight firms before loading up their plans with cargo. 

Analysts said that the apparent sabotage attacks marked a worrying escalation if confirmed to have originated from Russia.

John Foreman, a former British defence attaché in Moscow, said that Putin was showing a new “recklessness” in his attempt to “dishearten, deter and weaken the West”.

‘Biggest incident in aviation security in many years’

Philip Baum, associate professor of aviation security at Coventry University, said: “This is a game changer in world politics.”

He termed the attack the “the biggest incident in aviation security in many years”, adding: “Russia is a member of the International Civil Aviation Organisation, which is a United Nations body. Any recognised state doing this – what’s the implications of that for aviation security?”

The plane carrying the parcel was “certainly still carrying crew and could blow up over a population centre”.

DHL did not immediately respond when approached for comment by The Telegraph. In an earlier statement, it told The Guardian that it was working ”to secure its network, staff and assets as well as customer shipments” amid “ongoing investigations by authorities from several countries”.

Earlier this week, British counter-terror police disclosed that they were facing a four-fold increase in attempts by hostile states, such as Russia, to murder or spy on people in the country.

 Matt Jukes, the head of UK counter-terrorism police and a Metropolitan Police assistant commissioner, said: “I’m talking really here about spies, saboteurs, assassins and war criminals. That sounds quite Le Carre and potentially remote to a lot of people’s lives in the country.”

In April, Britain charged several men with an arson attack on a Ukrainian-owned logistics firm in London. They were alleged to be aiding the mercenary Wagner group.

Donald Tusk, the prime minister of Poland, said this summer it was “quite likely” that Russia was behind a blaze which destroyed a Warsaw shopping centre in May.

Moscow is also suspected of launching a failed plot to assassinate Armin Papperger, the chief executive of the German arms firm Rheinmetall, which plays a key role in supplying artillery ammunition to Kyiv’s forces.