A fire service spokesman said: ‘We received a call this afternoon around 12.25pm to a report of a fire on Chobham Common.
‘Ten fire engines have been sent in total, alongside multiple specialist vehicles, with the first arriving at the scene around 12.35pm.
‘Approximately 41 hectares of grass and undergrowth are alight. Crews remain at the scene tackling the fire.’
The blaze was so large it could be observed from central London.
The fire is thought to have caused ash to fall in areas located as far away as Windsor.
Councillor for Clewer East Amy Tisi tweeted: ‘Ash is now falling in my garden in Windsor.
‘I can only assume from #Chobham. It must be a huge fire.’
The fire caused the grand final of the Rose Ladies Series golf to be suspended.
Trains are currently unable to pass the railway at Longcross in Surrey due to the blaze approaching the area and parts of Chobham Road have also been shut.