British Prime Minister David Cameron has called a meeting of the government's COBRA emergency committee after army recruitment officers received a series of suspicious parcels.
Counter-terrorism police said suspicious parcels had been found at three army recruitment centres in southern England, the latest in a series of such incidents.
Bomb disposal units were sent to Brighton, Oxford and Slough to assess the packages and roads nearby were sealed off.
Earlier this week, similar packages were found at army careers offices in three other towns.
It was reported one of the packages contained a small explosive device.