Arm na Poblachta (ANP) is believed to have been responsible for leaving a "viable device" in Co Derry last week.
Police received a warning that two devices had been left in the Ballyquin Road area of Dungiven on Thursday.
Read More:
100 people unable to get to work in Co Derry security alert
Who are republican group Arm na Poblachta?
In a statement the PSNI said there was a security alert in the area on Friday and that “following a report that a suspicious object had been left in the area, officers attended the scene and cordons were put in place”.
They say the Ammunition Technical Officers (ATO) were called to the scene and declared the object “viable device”.
It was later taken from the scene for examination.
In August police sealed off an area around an industrial estate at Ballyquin Road and a small number of nearby homes were evacuated.
The alert later ended without anything being found.
Later that month an object was removed from the Carnanbane Road area of Dungiven by police after a security alert in the area.
It is understood that a security alert in the Feeny Road area in February was sparked after a republican group claimed that a device had been left in the area.
In August the names and addresses of three people it was claimed were PSNI officers appeared on a poster in Dungiven town.
It later emerged that the claim against one person was incorrect, while another had resigned from the force six months earlier.