Police in the UK are investigating claims that the 'IRA' is responsible for explosive devices found in London and Glasgow last week.
The devices were sent to three buildings in London - at Heathrow Airport, London City Airport and Waterloo Station - and to the University of Glasgow.
The packages contained "small improvised explosive devices."
Nobody was injured in the incidents.
However, one of the devices "initiated" after being opened by staff, resulting in part of the package burning.
Some of the suspicious packages are reported to have had Irish stamps.
According to Met Police and Police Scotland, a media outlet in the North yesterday received a claim of responsibility.
It was allegedly sent on behalf of the 'IRA'.
The MPS & @PoliceScotland are aware of the claim of responsibility, allegedly made on behalf of the ‘IRA’, for the devices that were received at three buildings in #London and at the University of #Glasgow on 5 and 6 March.
— Metropolitan Police (@metpoliceuk) March 12, 2019
It also claims five devices were sent, despite only four having been discovered so far.
Police say the claims were sent using a "recognised codeword".
In a statement, Met Police said: "Given the packages received last week bore similarities to devices sent in the past which were linked to dissident groups associated with Northern Ireland-related terrorism, officers were already looking at this as a line of enquiry. However, we continue to keep an open mind and enquiries continue.
"We are also aware that those claiming responsibility have indicated five devices were sent. At this time, only four devices have been recovered."
Justice Minister Charlie Flanagan said he was "deeply concerned" to learn about the latest developments.
He said: "As I previously said, this was a reckless and cowardly attack on the entire community. I condemn in the strongest possible terms the people who carried out this act."
"We must work together to reject those isolated groups who would discard the accomplishments of the peace process for all communities on these islands for their own narrow objectives.
"Their futile agenda will not succeed."
Minister Flanagan added: "I spoke to the Home Secretary yesterday and conveyed my utter disgust at these actions. They are the actions of those who are without any vision for a peaceful future on Northern Ireland.
"I also reaffirmed to the Home Secretary our deep commitment to working closely with our colleagues in Northern Ireland and the United Kingdom.’
The UK investigation, which is being led by counter-terrorism police in London, is continuing.
Members of the public are being urged to remain vigilant.
Businesses have also been told to report any suspicious packages to police.