Two giraffe subspecies have been classed as critically endangered for the first time.

Both the Kordofan giraffe, often found in Cameroon, and the Nubian giraffe, often found in Kenya, have been placed on a threatened species red list.

Researchers from The International Union for the Conservation of Nature's Species Survival Commission found the two subspecies were critically endangered, meaning they have an extremely high risk of extinction in the wild.

The Kordofan giraffe, pictured above, is now critically endangered. If their numbers continue to dwindle, they could go extinct in the wild, meaning they can only be found in zoos or in captivity [File photo]

The Kordofan giraffe is around 16 foot tall, which is relatively small for the giraffe, and has odd spots on the inside of its legs.

The Nubian giraffe can be up to 19 foot tall with sharp spots, and no spots on its underbelly.

If their numbers continue to dwindle, they could both go extinct in the wild, meaning they can only be found in zoos or in captivity.

The International Union for the Conservation of Nature publishes a nine stage extinction scale.

Dr Julian Fennessy, Director of the Giraffe Conservation Foundation, said giraffes were undergoing a silent extinction.

She said: 'While giraffe populations in southern Africa are doing just fine, the world’s tallest animal is under severe pressure in some of its core ranges across East, Central and West Africa.

'It may come as a shock that three of the currently recognised nine subspecies are now considered ‘Critically Endangered’ or ‘Endangered’, but we have been sounding the alarm for a few years now'.

Two giraffe subspecies have been classed as critically endangered for the first time. Both the Kordofan giraffe, often found in Cameroon, and the Nubian giraffe, often found in Kenya, have been placed on an extinction red list [File photo]

However, researchers also found that the numbers of two separate giraffe subspecies have increased.

The Rothschild's giraffe, also found in Kenya, has gone from endangered in 2010 to 'vulnerable'.

The West African giraffe also went from endangered in 2008 to 'vulnerable'.

The researchers said the downlisting was due to the efforts of African governments and conservation organisations.