Investigators looking into a suspicious device sent to the University of Glasgow are 'keeping an open mind' after it was claimed the 'IRA' was behind the incident.

Police Scotland said the package received by the campus last week bore similarities to the devices sent in the past which were linked to 'dissident groups associated with Northern Ireland-related terrorism'.

Officers were already looking at the group as a possible line of enquiry before the claim of responsibility was made on behalf of the 'IRA' to a media outlet in Northern Ireland using a recognised codeword.

READ MORE: One of five explosive packages sent to UK by 'IRA' unaccounted for

Those claiming responsibility have indicated that five devices were sent, however, only four have been recovered.

Businesses, sectors and the public are being urged to be vigilant and report suspicious packages to police.

The advice was previously sent to armed forces personnel and is being reiterated again in light of this claim.

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Police Scotland issued a joint statement with the Metropolitan Police following the discovery of three suspicious packages across London.

On Tuesday, March 5, at approximately 9.55am the Met Police received a report of a suspicious package at The Compass Centre, Nelson Road, Hounslow.

Read more: Glasgow University buildings evacuated after 'suspicious' package is discovered on campus

The package was opened by staff at the building, causing the device to initiate. This resulted in part of the package burning.

No one was injured. The building was evacuated as a precaution. Specialist officers attended and made the device safe. The Compass Centre is not within Heathrow Airport, and flights were not affected by this incident.

At approximately 11.40am, British Transport Police were called to reports of a suspicious package in the post room at Waterloo Station. The package was not opened. Specialist officers attended and made the device safe. No one was injured.

The station was not evacuated however cordons were erected in a small area on Cab Road, outside the station. Train services were not affected.

At approximately 12.10pm police were called to a report of a suspicious package at offices at City Aviation House, Royal Docks, Newham. Staff were evacuated from the building as a precaution.

The package was not opened and no one was injured. Specialist officers attended and made safe the device. Flights to and from the airport were not affected.

On Wednesday, March 6, a suspicious package was received at the University of Glasgow. The package was not opened and no one was injured. The emergency services were alerted and several buildings within the estate were evacuated as a precaution. Specialist officers subsequently carried out a controlled explosion of the device.

Read more: Glasgow University buildings evacuated after 'suspicious' package is discovered on campus

Detectives from the Met's Counter Terrorism Command are leading the investigation into the three packages received in London, whilst Police Scotland, under direction from the Crown, is leading the investigation into the package received at the University of Glasgow.

Both investigation teams are working closely together to share any information or intelligence that could assist their respective inquiries.

Enquiries continue and no arrests have been made at this time.

Suspicious activity can be reported by calling the confidential phone line 0800 789 321 or filling in a secure form at www.gov.uk/act. In an emergency always dial 999