The five lions are held in cages at Khartoum's Al-Qureshi Park in an upscale district of the capital, but for weeks now they have been suffering from shortages of food and medicine.

"I was shaken when I saw these lions at the park... their bones are protruding from the skin," wrote Osman Salih on Facebook as he launched an online campaign under the slogan #Sudananimalrescue.

"I urge interested people and institutions to help them."

Park officials and medics said the lions' conditions  deteriorated over the past few weeks, with some losing almost two-thirds of their body weight.

"Food is not always available, so often we buy it from our own money to feed them," Essamelddine Hajjar, a manager at Al-Qureshi park told AFP.

The park is managed by Khartoum municipality but also funded in part by private donors.

Sudan is in the midst of a worsening economic crisis, led by soaring food prices and foreign currency shortage.

On Sunday, crowds of citizens, volunteers and journalists flocked to the park to see the lions after their photographs went viral on social media networks.

One of the five cats was tied with a rope and was fed fluids through a drip as it recovered from dehydration, an AFP correspondent who toured the park reported.

Chunks of rotten meat covered in flies lay scattered near the cages.

The overall condition of the park itself was also affecting the animals' health, another official at the park said.

"They are suffering from severe illnesses. They are sick and appear to be malnourished," said Moataz Mahmoud, one of the caretakers at the park.

It is unclear how many lions are in Sudan, but several are at the Dinder park along the border with Ethiopia.

African lions are classified as a "vulnerable" species by the International Union for Conservation of Nature (IUCN).

Their population dropped 43 percent between 1993 and 2014, with only around 20,000 alive today.

str-jds/sw