Fake cosmetics, massage pillows and sex toys. Crude homemade explosives. A Russian known as Warrior. A code word: Mary.

These are among the key elements of a suspected Russian-run sabotage plot that led to three parcels being detonated at courier depots in Britain, Germany and Poland last summer, said a person with knowledge of the Polish investigation.

The pillows, packed into the parcels with the cosmetics and sex toys, contained hidden homemade incendiary devices made of a cocktail of chemicals including highly reactive magnesium, according to the person familiar with the case, who provided the most granular account yet of the alleged plot.