Scientists working to save the northern white rhinoceros from extinction plan to implant its artificially developed embryos in another, more abundant rhino subspecies in Kenya later this year, researchers and government officials said on Wednesday.

The northern white rhino came closer to extinction in 2018 when the last known living male died in Kenya's Ol Pejeta Conservancy. The only surviving northern white rhinos now are a mother and daughter, which also live at the site, making them the world's most endangered mammal.

Researchers collected sperm from male rhinos before their deaths and developed three embryos using eggs collected from the two living females last year. They plan to implant the embryos in female southern white rhinos, which are more populous.

"Despite the fact that more research is still needed, the team expects that a first attempt for this crucial, never before achieved step, may be undertaken in 2020," Ol Pejeta Conservancy said in a statement.

In addition to Ol Pejeta, the team behind the effort includes Kenya Wildlife Services, Italian-based Avantea Lab, which has the embryos in its custody, Dvr Krlov Zoo in the Czech Republic, and German-based Leibniz Institute for Zoo and Wildlife Research.

"We are glad that the northern white rhino in-vitro fertilisation project [...] has been able to successfully produce three pure northern white rhino embryos ready for implantation," Tourism and Wildlife Minister Najib Balala said.

"This is a big win for Kenya and its partners, as the northern white rhinos are faced with the threat of imminent extinction."

The northern white rhino was once found in several countries in east and central Africa but, as with other rhino species, its numbers fell sharply due to heavy poaching.

The International Rhino Foundation estimates there are roughly 18,000 southern white rhinos surviving, mostly in South Africa. It puts the total number of black rhinos at about 5,500.

Kenya, which was home to as many as 20,000 rhinos in the 1970s, now has about 650, mostly black rhinos.