Police searching an area of the People's Park in Portadown have recovered four suspected pipe bombs.
Police and navy bomb experts carried out searches in the People's Park in Portadown. MLA Doug Beattie said they were searching for Troubles-era munitions.
It is believed the searches involved dive operations in the Corcrain River.
Police on Tuesday afternoon said the searches had ended and that the pipe bomb devices uncovered were not viable. They also found working parts of a firearm.
Inspector Leslie Badger said: “The investigation is at a an early stage and we are working to establish how old the items are and whether this find is linked to historic terrorist activity.”
Upper Bann MLA Doug Beattie welcomed the searches.
"It is clear the PSNI have credible intelligence that some explosive ordnance may well have been dumped in the river or the surrounding area," he added.
"It shows the PSNI have absolute commitment to keeping all citizens of Upper Bann safe and I commend their courage and commitment and that of the military personnel taking part in this dangerous operation.”