A man has been released on bail as inquiries continue into the massive heath fire at Thursley Common, Surrey.
The 52-year-old, from Thursley, was questioned on suspicion of arson after being arrested on Friday night.
Sixty firefighters were still at the scene on Sunday afternoon, and Land Rover vehicles were being used to get closer to the remaining areas of fire.
English Nature said the blaze had been absolutely devastating, with nearly all the 400-acre heathland destroyed.
Fire crews were called to the National Nature Reserve at Thursley Common at 1230 BST on Friday.
English Nature said it had been "catastrophic for wildlife", with at least 90% of the heathland consumed by fire.
Spokesman Dick Lambert said: "To lose almost the entire site will make recovery incredibly difficult [and] a long and painstaking process."
English Nature said Dartford warbler birds on the heathland would have been harmed, with other species like sand lizards, tiger wood beetles and silver-studded blue butterflies virtually wiped out.
Smoke could be seen from 10 miles away in south Farnham on Friday
Surrey Police is telling members of the public to stay away from Thursley Common, Ockley Common and Elstead Common as the fire could become stronger again in dry and windy conditions.
A number of homes in Dye House Road, Thursley, which "appeared to be in imminent danger" were evacuated during Saturday.
Thursley Road remains closed between its junctions with Woolfords Lane and Dye House Road.
Meanwhile, six men were arrested on Saturday evening after a group of people racing horse traps broke through police cordons in Elstead, to the north of Thursley Common.
They were arrested for violent disorder after confrontations with fire crews and police officers in the village.