Seven black rhinos are dead after a botched relocation by Kenya Wildlife Service, the Daily Nation newspaper reported on Friday.

The rhinos, who are part of a critically endangered species, died in "unclear circumstances" at the Tsavo East National Park, the newspaper reported.

They were among 14 rhinos the state-run wildlife service (KWS) began moving last month from the capital Nairobi to Tsavo East.

Kenya had a rhino population of 1 258 in 2017 of which 745 are black rhinos, 510 are southern white rhinos and three were northern white rhinos, having grown from less than 400 rhinos in the 1980s. The white rhino is a near threatened species.

In May, three black rhinos were killed in Kenya's Meru National Park.

Poaching has risen in recent years across sub-Saharan Africa where armed criminal gangs have killed elephants for tusks and rhinos for horns. Often the animal parts are shipped to Asia for use in ornaments and medicines.

A KWS spokesperson was not immediately available for comment. World Wildlife Fund-Kenya said in a statement it was "extremely concerned" by the reports.