A Kenyan court has ordered the British Army to pay compensation for the blaze, which ravaged more than 4,800 hectares (12,000 acres) of land during a military exercise conducted by the British Army Training Unit in Kenya (BATUK).

The unit is based near the town of Nanyuki, some 200 kilometres (120 miles) north of the capital Nairobi.

"Two and a half years later, zero compensation has been given to the people affected," said lawyer Kelvin Kubai as he read out an "open letter to the British government" on behalf of the victims at a press conference.

The letter, signed by 7,000 plaintiffs, said "the British Army is actually using every trick from the colonial rule book to try and not pay the Kenyan people compensation".

Those affected are seeking compensation for environmental damage, as well as payment for medical problems such as "serious breathing difficulties" and "permanent issues with eyesight" which they say resulted from the fire.

"Many, many farmers have not been able to grow back the crops and regain the livestock that was lost in this terrible fire," the letter said.

Compensation for the fire is being managed by an intergovernmental liaison committee (IGLC), made up of representatives from both countries.

The authors of the open letter criticised the IGLC for asking for more proof of the damage caused by the blaze.

"They wish to insult us further by telling us we have to prove -- again -- the damage that their careless and arrogant soldiers caused," the letter said.

"The facts remain that the British Army destroyed the environment in Kenya where they are guests and they don't want to pay us for it," it added.

- 'The British must go' -

"Justice delayed is justice denied," the letter said, calling on the British government and King Charles to "stop treating Kenya like a colonial outpost".

At the end of the press conference, a few hundred people chanted "we want our money" and "the British must go," briefly blocking traffic before dispersing.

King Charles III and his wife Queen Camilla will visit the East African nation from October 31 to November 3, his first trip to a Commonwealth country since becoming king last year, and his fourth official visit to Kenya.

The British monarch will visit Nairobi and the port city Mombasa, but not the town of Nanyuki where the BATUK is based.

While the army base fuels the local economy, it has also been implicated in several controversies in the area.

The most high-profile case is the 2012 death of Agnes Wanjiru, 21, who was found dumped in a septic tank after she reportedly went out partying with British soldiers at a hotel in Nanyuki.

London has always assured its cooperation with the Kenyan investigation, which has so far produced no known public results.