By Barnaby Phillips
BBC News, Johannesburg
Botswana has strongly denied reports that some of the last bushmen living in the Kalahari desert have been forcibly removed from their ancestral land.
Most bushmen now live in camps outside the reserve
The British-based group, Survival International, has accused Botswana's government of ethnic cleansing.
The Botswanan government says bushmen have been leaving the Kalahari, but at their own request.
The bushmen, or San, were hunter gatherers who lived in the desert of southern Africa for thousands of years.
Their traditional way of life has all but disappeared in recent years, and the Botswanan government wants the few hundred still living in the vast central Kalahari game reserve to move to nearby towns.
Tension between the bushmen and the government has been growing.
Last month, the police fired rubber bullets at a crowd of bushmen protesters who were trying to enter the game reserve.
The police say they were attacked and acted with restraint.
Now Survival International says the Botswanan police have evicted dozens of bushmen from the reserve at gunpoint and set fire to their homes.
The Botswanan government told the BBC that, over the past three days, it has moved about 35 bushmen out of the reserve, but not at gunpoint.
It says the bushmen asked to be moved.
Survival International says the bushmen are being forced out so the government can exploit diamond reserves in the Kalahari.
The government denies this. It says that if the bushmen move to towns, it can provide them with water, schools and health.
It also says their continued presence in the Kalahari is a threat to wildlife.