A member of staff at The Sunday World newspaper in Dublin has been treated for chemical burns after opening a package containing sulphuric acid.
The package arrived at the paper's offices from Spain at the end of last month, but details have just been revealed.
Gardai and Interpol are investigating if it was sent in error or if it was a deliberate attack.
There was no specific threat in the parcel for either the paper or any staff member. It only contained the acid and a note giving the chemical breakdown of the substance.
Sulphuric acid is a highly dangerous acid which has been used in some deliberate attacks.