A parcel bomb the group calling itself the ‘IRA’ has claimed it sent to a British army recruitment officer may not yet have been discovered.
It was one of five devices the group - which is also referred to as the New IRA - said it posted to addresses in Britain last week.
Four of the five parcel bombs have been discovered, but it is believed one has not been detected.
In a statement using a recognised codeword, the paramilitary organisation claimed responsibility for sending the bombs to various locations in England and Scotland.
It claimed that three were sent to “commercial targets” while the remaining two were posted to British army recruitment officers.
The group said a device discovered at Glasgow University was intended for a British army recruitment officer who works there.
It claimed the remaining undiscovered device was also sent to a recruitment officer.
The organisation has claimed that all of the devices contained explosives.
Scotland Yard last week said specialist officers believed the packages contained “small improvised explosive devices”.
Major disruption was caused after three of the packages were discovered at Heathrow Airport, London City Airport and Waterloo train station.
The devices were sent in A4-sized postal bags, which contained yellow padded envelopes.
The device sent to Heathrow Airport burst into flames when opened, while the other two were dealt with by the British army bomb squad.
Pictures of the hand-written packages were later released by police in England.
All are believed have listed Dublin as the return address.
The stamps used on the parcel bombs appeared to be similar to some issued by An Post for Valentine's Day in 2018, featuring a heart symbol and the words "Love Eire".
The ‘IRA’ has targeted British army recruitment centres before.
In February 2014 it said it sent devices to seven military recruitment offices across the south east of England.
None of the devices exploded.
SDLP Policing Board member Dolores Kelly last night warned that people can suffer "horrendous injuries from letter bombs - they are indiscriminate and dangerous devices”.
The MLA said the parcel bombs must be seen in the context of arms finds along the border and other recent incidents.
“The whole of the north is under a severe threat warning - that has not diminished in 10 years,” she said.
“It is beholden on the Irish and British and all he political parties, and in particular groups on the middle ground, to coalesce.
“We need to stop glorifying the violence of the past.”
Meanwhile, republican sources claim an ‘IRA’ car bomb in Derry in January contained a type of explosive previously not used by the group.
The device, which exploded outside the courthouse in Bishop Street, destroyed the vehicle and caused minor damage to surrounding buildings.