A part of a bullet was found in the venue where the Taoiseach is due to open the Fine Gael Ard Fheis tonight.
The discovery was made earlier today when what is understood to be the shell of a shotgun cartridge was found around the stage area.
It led to the evacuation of the venue at City West in Dublin and a fresh security sweep.
Taoiseach Enda Kenny was not in the venue at the time.
The Finance Minister has played down concerns about a security threat at the event.
Arriving this evening Minister Michael Noonan was quizzed about the incident.
“I didn’t hear anything about security threats. I’ve been coming to Fine Gael Ard Fheis since the 70s – there are frequent security threats, we haven’t come across a real one yet,” he said.