Thamesmead scrubland the size of five football pitches went up in flames yesterday (July 2).
Four fire engines and 21 firefighters tackled the grass fire on Eastern Way at 6.13pm for around 90 minutes.
The cause of the fire is being investigated.
A London Fire Brigade spokesperson said: "The main causes of accidental grass fires are barbecues, cigarettes, discarded matches and glass bottles, which, when left on dry grass can concentrate the sun’s rays and cause fires.
"Firefighters advise that barbecues are never left unattended and are completely out after being used. Cigarettes should be carefully disposed of as they can easily ignite dry grass."