"What we found is of great significance, to be clear," said Police Commissioner Justin Kelly at a press conference on Friday, confirming that it was explosive material.
Irish public service broadcaster RTÉ reported that the bomb was to be brought to Northern Ireland, and that the type of bomb is one that can be placed under vehicles.
Police have not confirmed that the bomb was to be taken to the border city of Derry, but said the explosive device was discovered in operations against so-called republican resistance to British rule in Northern Ireland.
A woman in her 20s and a man in his 40s have been arrested.
