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13 December 2012, 15:05 | Updated: 13 December 2012, 15:08
The man, in his 30s and from the Norwich area, was arrested on suspicion of offences under the Explosives Act and remains in police custody.
Heart's being told a house in Middletons Lane in Hellesdon, Norwich is being searched in connection with the enquiry.
Detectives from Norfolk Police have placed a seal on the property and Army Explosives experts are helping them.
Neighbouring properties can be reassured that they are not in any danger.