A number of African countries have banned China from buying their donkeys, saying demand for the four-legged creatures has become unsustainable.

Niger announced a ban on the export of donkeys this month after trade of the animals increased by three times in the last year, mainly to Asian countries.

And Burkina Faso has also put a stop to the export of donkey skins, which are boiled to produce gelatin, a key ingredient in the traditional Chinese remedy ejiao – believed to improve blood circulation and cure conditions including dizziness, irregular menstruation and insomnia.

Increased demand for imported donkey skins follows a dramatic drop in China’s donkey population as the country has industrialised.

The number of donkeys in China has fallen from 11 million to six million since the 1990s, according to CNN.

Atte Issa, a Niger government official, told the BBC that around 80,000 donkeys had been exported from the landlocked African country this year compared to 27,000 last year.

“If the export continues the animals will be decimated,” he said.

The average price of a donkey has also increased by around three-fold, according to the broadcaster, and some livestock sellers are switching to donkey breeding as their trade has become so profitable.

“[Ejiao] is quite a popular ingredient in China that people may self-prescribe,” Chinese medicine expert Mazin Al-Khafaji told The Independent. “But there is a shortage, and there are fakes around as it’s very expensive.”

“It’s what we call a blood tonic, so it stops bleeding and strengthens the blood. It’s used for anemia or low blood cell count,” he said.

Workers measuring out various dried items at a Chinese medicine store in Hong Kong (Getty Images)

“It’s a hard gel, made from donkey hide, which is then dissolved in hot water or alcohol. It’s also used topically in a cream, for leg ulcers for instance.”

In Burkina Faso, the country’s reserve of 1.4 million donkeys was being “overexploited” by a boom in trade of their hides, mostly with China, the country’s public health director Adama Maiga told AFP.

Mr Maiga said exports in hides had soared from 1,000 in the first quarter of 2015 to more than 18,000 in the last quarter.

Now all slaughter would have to be done in “officially recognised” abattoirs.

Two Chinese nationals have set up a donkey slaughterhouse in west Kenya, according to the Daily Nation.

The government approved the new abattoir, where around 100 donkeys could be killed a day and exported to China, in April, reported the Kenyan national newspaper.

In pictures: Inside the Yulin cat and dog meat trade Show all 13 1 /13 In pictures: Inside the Yulin cat and dog meat trade In pictures: Inside the Yulin cat and dog meat trade China A cat climbs up the cage at the slaughterhouse, trying to escape. This cat was later rescued by Peter Li In pictures: Inside the Yulin cat and dog meat trade China A slaughterhouse butcher transfers a cat to a cage, to be handed off to Peter Li. Shortly after, Li rescued the cat from the slaughterhouse AP/Humane Society International In pictures: Inside the Yulin cat and dog meat trade China Two kitchen knives are shown stuck in an iron cage, which are used to butcher dozens of dogs and cats every day. These knives have to be sharpened daily due to the number of animals they're used to slaughter In pictures: Inside the Yulin cat and dog meat trade China Caged dogs sit on the side of Renminzhong Road, waiting to be transferred to a slaughterhouse in a narrow alley AP/Humane Society International In pictures: Inside the Yulin cat and dog meat trade China Workers are shown getting the day's dog and cat meat prepared for sale in the morning In pictures: Inside the Yulin cat and dog meat trade China Dog meat is displayed in the marketplace In pictures: Inside the Yulin cat and dog meat trade China Residents pick their dog meat from a stand on Riverside Road In pictures: Inside the Yulin cat and dog meat trade China A woman on her moped transports more than 10 dogs, which had just been slaughtered, to her market shop for sale AP/Humane Society International In pictures: Inside the Yulin cat and dog meat trade China Hundreds of pet dogs await their own death in a slaughterhouse, while they watch as their companions are slaughtered in front of them AP/Humane Society International In pictures: Inside the Yulin cat and dog meat trade China A group of cats from Sichuan Province arrive at Renmin Middle Road on a truck, and wait to be transported on carts to a slaughterhouse in a narrow alley In pictures: Inside the Yulin cat and dog meat trade China A truck arrives in Yulin with nearly 1,000 dogs of various breeds crammed into narrow wire cages with no space to extend their limbs. According to the driver, the truck came from Sichuan, 800 miles west of Yulin. The traumatized dogs waited in silence for the next stop on their journey In pictures: Inside the Yulin cat and dog meat trade China Dogs are hung up for sale for meat in Dong Kou market, as a dog looks on In pictures: Inside the Yulin cat and dog meat trade China Peter Li holds a puppy's collar found at a slaughterhouse AP/Humane Society International

Earlier this year, Chinese ejaio expert Qin Yunfeng offered an alternative solution to China’s donkey shortage, according to The New York Times.