A man has been arrested in Somerset under the Terrorism Act.
Police are searching a property in Paulton after he was held on Thursday on suspicion of making or possessing an explosive substance.
On Friday he was re-arrested under a section of the anti-terror laws that allows detention if a person is suspected of being concerned in terrorism.
Officers wearing protective clothing are carrying out the search.
The Explosive Ordnance Disposal Team has been called as a precaution.
The suspect, who is 33 and from Somerset, is in police custody.
Chf Insp Steve Kendall said “There is no wider threat to the public.”