Kenyan wildlife authorities say a tenth critically endangered black rhino has died after being moved from the capital to a new wildlife park.

The country's wildlife minister, Najib Balala, says the one surviving rhino has been injured after being attacked by lions in what some conservationists have called a national disaster.

The Kenya Wildlife Service's (KWS) acting director has been fired and several other officials have been suspended after "clear negligence" was found in the rhinos' transfer to Tsavo East National Park Rhino Sanctuary.

Balala said preliminary investigations show the rhinos died from stress intensified by salt poisoning as the animals struggled to adjust to saltier water in their new home.

Save the Rhino International, a U.K.-based conservation charity, estimates that there are fewer than 5,500 black rhinos in the world, all of them in Africa, while Kenya's black rhino population stands at 750, according to the Worldwide Fund for Nature.

Transporting wildlife is a conservation strategy used to help build up animal populations.

Between 2005 and 2017, 147 black rhinos were transferred to new habitats in Kenya, the tourism ministry said. Just eight died following those transfer operations.

According to KWS figures, nine rhinos were killed in Kenya last year.

In May, three were shot dead inside a protected sanctuary in northern Kenya and their horns were removed, while in March the last male northern white rhino on earth, an elderly bull named Sudan, was put down by Kenyan vets after falling ill.

Rhinos have few natural predators because of their size and thick skin but are targeted by poachers for their horns which are highly valued in parts of Asia where they are believed to have medicinal qualities.

Huge demand from China and Vietnam where the horns can fetch tens of thousands of dollars has led to a collapse in the number of rhinos in the wild.