A suspicious package delivered to Aldershot Army Careers Centre is one of seven being investigated, and thought to be linked to the IRA.
A 'suspect package' was delivered to the centre, in Hospital Hill, on Wednesday morning (February 12) and a Ministry of Defence (MoD) bomb disposal unit was deployed to the scene at around midday to 'make it safe'.
Three more similar packages were delivered to army careers offices in Oxford, Brighton, Canterbury and Slough's Queensmere Shopping Centre the next day. These added to packages sent to offices in Reading and Chatham, Kent, on Tuesday.
The security scares resulted in people being evacuated from the area in some locations.
The South East Counter Terrorism Unit (SECTU) is investigating the incidents.
A spokesman for No 10 Downing Street said the ‘small, crude, but potentially viable devices bearing the hallmarks of Northern Ireland-related terrorism’ had all been safely dealt with by police.
In Aldershot, officers from Hampshire Constabulary closed Hospital Hill and Knollys Road while the investigation took place. All roads were reopened at around 1.30pm. Witnesses said they saw a dog unit at the scene.
Detective Superintendent Stan Gilmour at the SECTU said: "The contents of the packages are suspicious in nature and will now be sent off for forensic examination.
"Even if the contents are determined to be a viable device they pose a very low level threat and are unlikely to cause significant harm or damage.
"When a suspect package is reported we have a routine response which means we may need to evacuate the area if necessary until we can be sure it poses no threat to the public. Whilst this can cause concern and disruption for local communities, it is a necessary precaution until we know what we are dealing with."
Advice has been sent to the Royal Mail and to the MoD to ensure staff remain vigilant and contact police if they have any concerns about packages.