THE cause of the Wareham Forest Fire was "accidental due to social activity in forest," firefighters say.

Dorset & Wiltshire Fire and Rescue Service (DWFRS) has undertaken a full investigation into what sparked Monday's blaze, which affected 190 hectares of land – and they have concluded it was not deliberate.

One likely cause is a disposable barbecue or campfire.

A DWFRS statement said: "We now believe the cause of this fire to be accidental, due to social activity in the forest.

"While we cannot pinpoint the exact cause, we have found evidence of multiple disposable barbecues, campfires and glass bottles."

At its height the fire front stretched across three kilometers and needed more than 150 firefighters to bring it under control.

Strong winds fanned the flames, which left billowing smoke visible across the Bournemouth conurbation.

Residents were even advised to close their doors and windows.

Now, with warm weather forecast in the next few days, DWFRS is on amber alert for even more wildfires.

They said: "This means that, should we experience another wildfire, it could spread quickly and easily due to the dry and windy conditions.

"As we have seen here, wildfires take a great deal of resources and time to bring under control.

"Please stay fire-aware when out and about and please stay vigilant.

"In light of all of this, please do not have campfires or use disposable barbecues in our forests and heathlands."

Around 50 firefighters remain on scene today, damping down and monitoring hot spots.

Smoke continues to rise from the forest.

DWFRS said: "We again ask walkers and cyclists to avoid the area, there are lots of fire appliances moving around, some five miles of hose laid out, and hot spots can flare with little or no warning. Please help us by staying away."