Blood from sheep butchered in a religious ritual at one of South Africa's busiest tourist beaches could lure sharks towards those in the water.

The Leader of the Healing Oracle, Prophet Moses Michael said the ritual was inspired by the Old Testament to help cure sick people.

Biologist Sheldon Dudley of the Natal Sharks Board told a Reuters reporter that, "putting blood or offal into the water is simply not sensible...a shark in the vicinity of the beach may come to investigate."

Animal protection officers said they were also investigating cruelty allegations around the sacrifices, and an official supervising the Durban beach said they were unacceptable.

"A beach is a public place and we can't have animals being sacrificed in front of visitors and children," the beach official told Durban's daily news.