Two men aged 22 and 35, and two men, both aged 55, who were arrested by detectives on suspicion of terrorism-related offences, have been released from police custody following questioning.
The men were arrested in connection with a three-day security alert in the Dungiven area that ended on Monday evening, February 26.
A viable pipe bomb device was made safe on Sunday evening in the Curragh Road area of Dungiven.
Detectives are continuing to appeal for information and anyone that could help with ongoing enquiries into the investigation is asked to call 101, quoting reference number 1210 24/02/23.
You can also submit a report online using the non-emergency reporting form via http://www.psni.police.uk/makeareport/
Or you call Crimestoppers anonymously on 0800 555 111 or online at http://crimestoppers-uk.org/
