UTV News is reporting that Army bomb experts are being sent to the scene of the small explosion in Belfast Cathedral quarter.
There are reports that restaurants and other premises in the area are being evacuated.
More top news
ITV Border Political Editor Peter MacMahon says it's far too early to call this referendum.
A World War Two veteran has told ITV News he has fulfilled a boyhood dream by voting for an independent Scotland.
Speaking as a Scot - not the ITV News Scotland Correspondent - I am feeling a great anxiety about what lies ahead.