According to the park director, some buffalo have also been killed, while noting that although tests have confirmed that the deaths were caused by anthrax poisoning, the exact cause of the poisoning is still unknown.

At least 50 hippos and other large animals have been killed by anthrax poisoning in Virunga National Park, the oldest African park located along Eastern Congo.

The Virunga Park director, Emmanuel De Merode, disclosed this on Tuesday.

The animals were found floating motionless along the Ishasha and Lake Edward River. Images shared by the national park showed them lying on their backs or sides on the banks of the river.

About 25 hippopotamus bodies were seen floating in the lake.

According to the park director, some buffalo have also been killed. He said although tests have confirmed that the deaths were caused by anthrax poisoning, the exact cause of the poisoning is still unknown.

Anthrax is an infectious disease caused by the bacterium Bacillus anthracis, which forms spores that can survive in the environment for decades.

The disease affects both domestic and wild animals, which can become infected if they inhale the spores in contaminated soil, plants, or water.

Humans can also be infected through contact with contaminated animal products, inhalation of spores, or ingestion of undercooked, contaminated meat.

In a statement on Tuesday, the Congolese Institute for Nature Conservation advised locals to steer clear of wildlife in the region and to ensure any water from nearby sources is boiled before consumption.

The park director also said that a team was on-site and that they were trying to get the hippos out of the water and bury them, but that it was difficult because they did not have excavators.

"It's difficult due to lack of access and logistics. We have the means to limit the spread (of the disease) by...burying them with caustic soda," Reuters quoted him as saying.

He stated that the park rangers first realised something was wrong when dead animals began turning up along the Ishasha River, which marks the border between Congo and Uganda, around five days ago.

The river flows through a region controlled by rebel factions.

However, the recent deaths of endangered bulls mark a significant setback for the park, which has been striving to boost the hippo population in recent years.

Uncontrolled poaching and conflict had reduced the number of hippopotamuses from over 20,000 to just a few hundreds by 2006.

Currently, the park is home to approximately 1,200 hippopotamuses.