The PSNI is facing calls to investigate how a parcel bomb addressed to a republican support group in Scotland was left lying in a police station for two weeks.

Police confirmed the viable device, which was addressed to Cairde na hÉireann (Friends of Ireland) in Glasgow, is similar to parcel bombs sent to Celtic manager Neil Lennon last month.

It emerged last week that the devices sent to Lennon and two other high-profile supporters of the club, Paul McBride QC and MSP Trish Godman, had the capacity to kill.

The Royal Mail’s National Return Letter Centre is based in Belfast and all undelivered mail is sent there.

It is understood the deadly package at the centre of Tuesday’s alert was redirected to Belfast from Scotland after postal staff failed to deliver it.

Police have said the device did not originate in Northern Ireland. It has emerged that suspicions about the device were first raised on April 12 at Tomb Street sorting office.

It was then taken to Musgrave Street PSNI station, where it remained until this week when a fresh alert was sparked after police said they received fresh information.

A total of five devices have now been intercepted by police investigating the parcel bomb plot against the Celtic chief and others.

Cairde na hÉireann national organiser Franny McAdam said his group was targeted because it highlights anti-Irish racism in Scotland.

Policing Board member Dominic Bradley said the PSNI must establish how the parcel bomb ended up sitting in a police station for two weeks.

He said: “It beggars belief that a dangerous and viable device was stored in such a way, putting the lives of police officers and civilian staff at risk.”

A spokesman for the PSNI last night refused to reveal how many police officers and civilian staff handled the device after it was removed from Tomb Street.

He said police could not discuss the issue as there was an “ongoing investigation”.

While police on this side of the Irish sea are staying tight-lipped, Strathclyde Police have renewed their appeal for help in catching the parcel bomber.

Chief superintendent Ruaraidh Nicolson said: “Naturally the public are going to be concerned about the latest discovery, however we would like to emphasise that this device is not a new one, it entered the postal system at the end of March, around the same time as two of the other packages.”

Meanwhile, Mr McAdam said his organisation was targeted because it tackles anti-Irish sentiment in Scotland.

He said: “For too long now people in authority have refused to recognise any attacks on the Irish community as anti-Irish racism, and indeed some councils, like Kirkintilloch and Falkirk, deny it even exists.

“People in positions of power need to stop burying their head in the sand and stand up against racists.

“We at Cairde na hÉireann will continue to fight against racism and sectarianism wherever we encounter it.”

Belfast Telegraph