A security alert on the Lagan last night was sparked by "suspicious items" found while the river was being dredged.
PSNI's Terrorism Investigation Unit have launched an investigation following the discovery, which they believe to be a "significant munitions find".
Pictures from the scene suggest the items were found in a red hold-all.
The Queen Elizabeth Bridge and Lagan footbridge have now been reopened to the public.
A spokesperson for the service said: "The Queen Elizabeth Bridge in Belfast and a nearby footbridge have both re-opened following closure last night (Thursday, 30 January) due to a security alert.
"The alert was sparked after a number of suspicious items were discovered during dredging work being carried out in the river.
"ATO attended the scene and examined the objects, which have been taken away for further forensic examination.
"Detectives from PSNI Terrorism Investigation Unit have launched an investigation."
Detective Chief Superintendent Raymond Murray added: "While the objects will undergo further examination, we believe a significant munitions find has been uncovered."
