The smoke plume seen from south Farnham - about 10 miles way

Surrey Fire and Rescue Service said it received numerous 999 calls to report the fire at Thursley Common, which threw up a huge plume of smoke.

Visitors to the English Nature beauty spot were told to leave immediately and 20 houses in Thursley Road, Churt, were evacuated and the road closed.

English Nature said it was too early to assess damage to the 400 acre heath.

A fire service spokesman said conditions were ideal for a grass fire to spread.

"It is dry and there are very strong winds. It is a major incident."

The fire spread quickly and covered a large area of the reserve. Simon Nobes

Firefighters were called at 1230 BST and were beginning to bring the fire under control at 1800 BST.

"We are formulating a plan to make sure we have it surrounded so that it doesn't spread any further," the spokesman said.

Once the fire was out firefighters would have to make sure it did not flare up again as the ground was extremely dry.

One fireman was treated for burns at the scene and two others for heat exhaustion.

Thursley is one of the largest remaining fragments of Surrey heath and supports a rich wildlife including ground nesting birds such as nightjars, woodlark and Dartford warbler.

"This was a good nesting year for these birds - especially nightjars - and the fire has passed through known nesting areas," said site manager Simon Nobes.

"An area of heath that supports the very rare wood tiger beetle has also been burnt.

"The fire spread quickly and covered a large area of the reserve.

"We will be inspecting the site over the next few days to see the extent of the damage."