An apparent firebomb attack at a DHL warehouse in Birmingham, linked to Russian-backed saboteurs, was believed to be a trial run for a US attack, according to Polish officials.
Poland’s National Prosecutor’s Office has confirmed four arrests after parcels “containing explosives” were allegedly sent via courier companies to countries including the UK.
Counter-terror police in the UK are already investigating whether Russia had any involvement after a suspicious package caught fire at a DHL warehouse in Minworth in July.
Authorities in Germany are also examining several fires thought to have been caused by incendiary devices hidden inside parcels at a warehouse in Leipzig.
Polish Prosecutor Katarzyna Calow-Jaszewska said the latest arrests were related to parcels “which spontaneously ignited or detonated during land and air transport” to EU countries and the UK.
She said the group’s goal was allegedly “to test the transfer channel for such parcels, which were ultimately to be sent to the United States of America and Canada”.
She added that four people involved in “sabotage” and “of an international nature were detained”.
On Monday, Counter Terrorism Policing said the arrests reported by Polish authorities were not carried out as part of its investigation.
It coincides with reports by the Wall Street Journal (WSJ) that the devices were “electric massagers implanted with a magnesium-based flammable substance” and “part of a wider Russian plot”.
Russia has denied involvement. A Kremlin spokesperson told the US newspaper the claims were “traditional unsubstantiated insinuations from the media”.
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A suspicious fire took hold in July at a DHL warehouse in the UK after a package arrived by air, but further details about the plane and its flight path are unknown.
Last month British police said their investigation was “being led by officers from the Met’s Counter Terrorism Command with support from colleagues from Counter Terrorism Policing West Midlands”.