The fire broke out on Saturday and was still destroying the park 36 hours later, as firefighters tried to put it out before it spread further into the forest.
While sleeping at the Treetops hotel, a remote game-watching lodge constructed high into a tree in the Aberdare forest, Britain’s Elizabeth II, then a princess on a visit to Kenya, received news of her father’s death.
Rhino Ark, a Kenyan conservation organization, said it has dispatched helicopters to undertake aerial inspections of the area in order to assess the amount of forest damage.
“Thirty-five trained firefighters have been deployed by chopper on the southern fireline,” the group said on Twitter Monday.
“We have firefighters who are doing a decent job up there. So far so good, they are managing to control it but it has not been completed,” Rhino Ark official Adam Mwangi told AFP.
“Definitely it is a fire caused by human activities,” Mwangi said, as speculation mounted about the possibility of arson.
The park lies some 100 kilometres (60 miles) north of the capital Nairobi in the Aberdare mountain range.
It is home to spectacular waterfalls and lush bamboo jungles as well as a variety of wildlife including leopards, elephants and critically endangered black rhinos.
The Aberdares are the third highest mountain range in Kenya, reaching a summit of just over 4,000 metres (over 13,100 feet).
In recent days, concern has grown over a contentious proposal before parliament which could allow politicians to determine if public forest can be carved out and handed over to private interests.
The amendment to the Forest Conservation and Management Act –- reforms passed after decades of rampant land clearing — has roused significant community anger and sparked fears that it could result in unchecked logging and environmental destruction.