A suspected bomb discovered in Brighton is being examined by experts today as part of a national terror alert.

The package, which was discovered at an army recruitment office, sparked a major alert which closed a large section of the city centre with hundreds of people evacuated from shops and offices.

Counter-terrorism police and ministry of defence bomb disposal experts were called out after the package was discovered at the army careers office in Queen’s Road at 10am yesterday.

The discovery of the package and others at locations across the UK prompted Prime Minister David Cameron to chair a meeting of the Government's Cobra emergencies committee.

Queen’s Road was cordoned off from Churchill Square to its junction with North Street until around 2pm.

Vehicles and pedestrians were diverted as military police, Sussex Police, MoD bomb officers, firefighters and counter-terrorism officers gathered at the scene.

The surrounding roads which were also cordoned off included Windsor Street and Portland Street.

At the same time as this was going on virtually identical packages – feared to be bombs – were being discovered across the south.

They were discovered in RAF Mildenhall, at Suffolk St Giles in Oxford and at army offices at Queensmere Shopping Centre in Slough and St Peter’s Street, Canterbury.

On Wednesday a suspect package was delivered to an army recruitment office in Hospital Hill in Aldershot.

On Tuesday similar packages were discovered in army recruitment offices in St Mary’s Butts in Reading and at The Dockyards in Chatham, Kent.

Yesterday (THURS) it was confirmed the envelope discovered in Chatham was a “viable bomb”.

It is likely to be a number of days before police can confirm whether the packages discovered yesterday (THURS), including Brighton, were also genuine bombs.

A police source said the threat to army officers was “low level but viable”.

Sussex Police Chief Inspector Dave Padwick (COR), explaining yesterday’s incident, said: "When a suspect package is reported we have a routine response which means we may need to evacuate an area until we can be sure it poses no threat to the public.

“The contents of other similar packages received at army careers offices over the last few days are still being examined but it is clear that even if they do turn out to be viable devices they are extremely low level and unlikely to cause any significant harm or damage.”

He added: “We would like to thank their public for their continued patience and understanding through the day while we dealt with this incident.

“The priority has to be making sure the area is safe."

A Ministry of Defence spokesman said: "We can confirm that we are aware of security incidents ongoing in Oxford, Slough and Brighton involving armed forces careers offices.

"The relevant police authorities are investigating with military explosive ordnance disposal teams in support and any further inquiries should be directed to the police.

"Security advice has been reiterated to our personnel."

Detective Superintendent Stan Gilmour, of the south east counter terrorism unit, yesterday (THURS) said: "Because suspicious packages were found at various locations yesterday, notes were sent out to all the army careers offices, as well as the Post Office, asking staff to be extra vigilant and look out for any suspect packages."

A Kent Police spokesman, discussing the Canterbury incident, said: "Police were called to St Peter's Street at midday to reports of a suspicious package at the army careers office.

"Police at the scene have set up a cordon, and are investigating."

Detective Superintendent Stan Gilmour of 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 also 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.