A section of Ngong Forest near Karinde, is on fire.
Sources indicate that the fire brigade is at the scene of incident trying to contain the fire that started about an hour ago.
Mt Kenya and Aberdare national parks were earlier on in the month on fire where at least 100,000 and 700 hectares of vegetation, respectively, were destroyed.
Kenya Wildlife Service Chief Warden Bajila Kofa said the fire at the Aberdares was caused by honey gatherers and community activities, with residents burning grass to kill ticks.
The cause of fire at Mt Kenya is yet to be established.
Meanwhile, the parliamentary Environment and Natural Resources committee led by Kareke Mbiuki called for strict measures to keep intruders out of forests.