The latest letter bomb attack was foiled only by good luck, it was revealed yesterday.

It is thought that the device was sent from within Scotland and was addressed to Cairde Na H'Eireann, or Friends of Ireland, in the Gallowgate area of Glasgow.

A senior figure in the Irish republican group told how postmen tried to deliver the package to their shop on two occasions before it was sent to the Royal Mail’s UK national return letter centre in Belfast.

The is the fifth device to be discovered in a string of foiled bomb attempts.

Investigators said that the device was similar to that sent to Celtic football manager Neil Hannon, QU Paul McBride and Labout MSP Trish Godman.

Cairde Na H'Eireann organize events such as the James Connolly march through Edinburgh and the annual Bloody Sunday march in Glasgow. The group also campaigns against racism and sectarianism in Scotland.

Speaking about the find, Frank McAdam the national organizer with Cairde Na H'Eireann said “We're deeply worried about our staff in here. We see it as anti-Irish racism.”

“We've had a big campaign against anti-Irish racism for the past couple of years, and it seems like any time we do a march and any time we highlight anti-Irish racism, something happens. We've received death threats in the past. We've had people within the organization attacked," he told the Scotsman.

Chief Superintendent Ruaraidh Nicolson, of Strathclyde Police said the posting of the device was an "irresponsible and appalling crime".

"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," he added.