Finnish police say they have arrested an 18-year-old man who ordered 22lb of fertiliser from Poland to make explosives.
Local media quoted officers as saying the man wanted to experiment with making his own fireworks.
The Finnish National Bureau of investigation says agents grew suspicious when the man received a package of fertiliser, which contains ammonium nitrate and can be used for making explosives.
Police said they arrested the man in the town of Lahti in southern Finland after searching his home.
They said that during the search, a number of things were confiscated "and these things were meant to manufacture an explosive device".
Police said the case has no connections to the massacre of 76 people in Norway on Friday.