A 17-year-old boy was arrested on suspicion of arson after derelict Southsea nightclub Joanna’s was destroyed in a blaze.
Police quizzed the teenager on Saturday in connection with the fire, which broke out at the South Parade building.
He was later released without charge.
Police and Hampshire Fire and Rescue Service are still probing the cause of the fire and have not ruled out arson.
As reported in The News, specialist teams were called in to trawl through rubble at the site to check no-one was trapped inside the building when the blaze broke out at about 6pm last Tuesday.
Remains of the former nightclub are expected to be demolished later this week.
Now police are renewing their appeal for witnesses.
Portsmouth Chief Inspector Richard Taylor said: ‘We’re keeping an open mind about how this fire started. We must explore and examine every line of inquiry thoroughly and this means a criminal motive cannot be ruled out.
‘As part of the police investigation, we needed to ensure that no people were in the building at the time of the fire. A routine search of the rubble was completed and we’re satisfied that there is no evidence at the moment to suggest this was the case.
‘We realise that some local residents have concerns about why they cannot return to their homes yet.
‘The community has displayed tremendous patience and understanding in helping us keep the public safe in the dangerous aftermath of a serious fire. We’re most grateful for this invaluable co-operation. Specialist officers with experience and expertise in these types of investigations are working as quickly as they can to progress our inquiries to a point where people can return home.
‘One week after the fire, we remain particularly interested in any movements of people and property, which may have been at or around the building on Tuesday, August 9 between 8am and 6pm.
‘As a result of our previous appeal, detectives have now identified and spoken with a blonde woman who was near the scene of the fire last Tuesday evening. She is not suspected of any crime and we’d like to thank her for coming forward to help our inquiries.’
Call CID at Fratton police station on 101 or Crimestoppers anonymously on 0800 555 111.