The discovery of 'hazardous and potentially explosive' items has seen a 12 storey block of flats in central Brighton evacuated, police confirmed.
In a statement it said officers arrived at Highleigh on Grove Hill at 7.20am and those living in the flat block have been evacuated and a cordon has been put in place for safety reasons.
It added: "The EOD (explosive ordnance disposal) have been informed and are on their way to the scene to make it safe for all concerned.
"No-one is believed to be in the concerned flat presently and enquiries to trace the resident are on-going."
Detective superintendent Carwyn Hughes said: "We are currently on scene and we are advising residents to avoid the area for the time being.
"I want to reassure those in the area and wider community this is not being treated as terrorist related activity at this stage. We are working with the EOD, East Sussex Fire and Rescue and Brighton and Hove City Council to make the area safe as soon as possible."