Firefighters are asking the public and residents if they know where their children and family members are after another wildfire overnight at Moors Valley Country Park.
Crews from Verwood, Christchurch and Ringwood were called at just before one o’clock on Saturday morning.
They used hose reels and beaters to put out the fire which covered around 25 by 50 metres of land.
It was the third fire at Moors Valley in the space of a week with other recent blazes at Canford and Upton heaths.
Dorset and Wiltshire Fire & Rescue’s Fire Investigation lead, Group Manager Shaun Milton, said: “We are working hard with Forestry England, Dorset Police and other key partners to try to stop these fires from occurring.
“But I am frustrated to have had to go back to the forest to witness the mindless destruction of this beautiful habitat.
“However, whilst in the forest overnight I spotted an individual on their bike.
“This has been reported to the Police, but I would ask residents and parents to make sure they know where their children and family members are overnight.
“We are continuing to work with the police to establish the cause of the fires.”
Superintendent Claire Phillips, of Dorset Police, said: “We recognise the damage recent heath and forest fires have caused to the natural habitat as well as the risks they pose to members of the public in the area.
“We are fully committed to working with our colleagues in the fire service to establishing the causes of these fires, and where they are suspected to have been started deliberately, we will be carrying out a full investigation to identify those involved.
“We would also urge members of the public to play their part by heeding warnings from the fire service in relation to refraining from having open fires or barbecues in these areas and also to make sure they report any suspicious activity to us.”