A group calling itself the IRA claimed responsibility for the packages
This parcel was sent to Waterloo Station in London (Image: Metropolitan Police/PA Wire)
Police have issued an urgent plea to postal workers as the investigation into parcel bombs which were sent to London and Glasgow ramps up.
Officers have urged those who may have come into contact with the devices, sent via post to major transport hubs in the capital as well as to Glasgow University between March 1 and March 22, to get in touch.
Detectives are linking the parcel bombs sent two months ago to packages dispatched to British Army Recruitment Centres in 2014.
On March 5 three packages containing small incendiary devices were delivered to transport hubs in London on March 5.
A fourth package was recovered at the University of Glasgow the following day.
A fifth package was recovered, having been returned to a postal depot in Limerick, Ireland, on March 22.
This package has since been forensically examined and is being treated as part of the same series.
The Charing Cross parcel (Image: Metropolitan Police/PA Wire)
A group calling itself the IRA, known to police as the New IRA, claimed responsibility for the earlier packages and said a fifth had also been sent.
Further analysis of the five packages has been carried out by forensic experts and, due to particular similarities between the devices and the methodology, the investigation teams are now formally linking the packages to those sent to various British Army Recruitment Centres in 2014.
'Packages sent by a violent dissident republican group'
Deputy Assistant Commissioner Dean Haydon, senior national coordinator for the UK's Counter Terrorism Policing, said: "Our inquiries continue, but clearly a key element of the investigation now is the link between the devices previously sent in 2014, and the five sent earlier this year.
"As with any investigation, we will be led by the evidence, but at this stage, our principal line of inquiry is that the devices were sent by a violent dissident republican group.
This device was uncovered in Limerick (Image: Metropolitan Police/PA Wir)
"The devices that were sent not only put their intended recipients in danger, but also endangered the lives of all those who handled and processed the parcels both in the Republic of Ireland as well as the UK.
The Glasgow package (Image: Metropolitan Police/PA Wire)
He added: "We are looking to identify any postal workers who may remember handling any of the packages between March 1 and March 22.
"We have recovered forensic evidence following examination of the devices.
"You may have information that could help us with our investigation and it would also help with our forensic inquiries to be able to eliminate anyone who may have innocently come into contact with any of the five parcels after they were posted."
"This was an extremely dangerous and reckless act and I would urge anyone who may have information about those responsible to contact police."