ARSONISTS are being blamed for a fire in a derelict accommodation block at Portland's former HMS Osprey site.

Twenty-five firefighters battled the blaze for an hour and half yesterday as it swept through the three-storey block formerly used as naval accommodation.

The 50-metre high building was severely damaged by the blaze yesterday morning. A full investigation will be carried out once the site is safe.

A spokesman for Dorset Fire and Rescue Service said the fire spread to all three floors but nobody was injured.

She added: "There was severe fire damage to the entire building. It was believed to have been started deliberately."

The emergency services were alerted to the blaze by a phone call from a member of the public.

Det Sgt Steve Broadhurst, of Weymouth CID, said: "We are keeping our minds open about the cause of this fire until our experts can fully examine the site.

"At the moment the site is too dangerous for a thorough examination. If anyone has information about the fire or saw or heard anything suspicious in that area since Wednesday evening, please ring our police line on 01305 222500 or Crimestoppers on 0800 555111."

Last year arsonists attempted to burn down another accommodation building on complex following proposals to use it as a centre for asylum seekers.