Ms Calow-Jaszewska said in a statement that a group of foreign intelligence saboteurs had been involved in sending parcels containing hidden explosives and dangerous materials via courier companies. The parcels then spontaneously burst into flames or blew up.
Western officials believe the fires originated in electric massage machines containing a “magnesium-based” substance.
Magnesium-based fires are hard to put out, especially on board a plane.
“The group’s goal was also to test the transfer channel for such parcels, which were ultimately to be sent to the United States of America and Canada,” Ms Calow-Jaszewska said.
On three days in July, fires broke out in a container due to be loaded on to a DHL cargo plane in the German city of Leipzig, at a transport company near Warsaw, and at Minworth near Birmingham, UK, involving a package described as an incendiary device.
The incident at Jablonow near Warsaw took two hours to extinguish, according to Polish reports.
UK officials have given few details about the Minworth fire on 22 July. Last month the Guardian newspaper reported that counter-terrorism police were investigating whether Russian spies planted a device in a parcel that later caught fire at a DHL warehouse. The parcel is believed to have arrived by air.
Ken McCallum, head of the UK’s domestic intelligence agency MI5, said last month that Russian secret agents had carried out “arson, sabotage and more dangerous actions conducted with increasing recklessness” after the UK had helped Ukraine in Russia’s war.
In Germany, the head of the domestic intelligence agency (BfV) has said it was only by a stroke of fortune that the Leipzig device had not ignited in mid-air.