"This is a tragic accident and we are deeply saddened by the loss of another endangered white rhino," said Dinokeng projects CEO Dawn Robertson.

"Animal and nature conservation is at the heart of our work in the DGR and the loss of any animal is a cause for major concern."

The bull rhino was crossing the Rust de Winter road, a public road passing through the game reserve, when it was hit by a truck. The driver of the truck was not injured.

"We not only have to protect our rhino from poachers, but we also have to ensure that all necessary action is taken to ensure that motorists abide by the speed limit to ensure their safety as well as that of the animals in the reserve," said DGR management association chairman Etienne Toerien.

He said Tshwane metro traffic police provided traffic enforcement services in the DGR.

"They trap and fine motorists found to be speeding or driving recklessly."

He said the Dinokeng Project was also in the process of installing 14 speed bumps on the tarred roads in the game reserve to encourage motorists to reduce their speed and abide by the 60 kilometres an hour speed limit.

"We often see poachers as the only threat to rhinos, but we all have a part to play in ensuring they are kept safe. Motorists must stick to the speed limit and exercise caution when driving in a game reserve," he said.