Parks authorities in Zimbabwe are investigating the mysterious death of 11 elephants in a forest in the west of the country after ruling out cyanide poisoning and poaching.

The carcasses of the elephants were discovered on Friday in Pandamasue forest, located between Hwange national park and Victoria Falls.

Blood samples have been taken to a laboratory for analysis to determine the cause of their deaths, said Tinashe Farawo, a spokesman for the Zimbabwe National Parks and Wildlife Management Authority.

The dead elephants were found with the tusks still on their bodies, ruling out poaching. In recent years poachers in Zimbabwe have poisoned dozens of elephants and taken their tusks to sell them to illegal ivory traders.

“We can only ascertain the cause of death after the tests. But we have ruled out cyanide poisoning,” Farawo said.

“Only elephants were affected. No vultures or any other animals were affected. Initial tests show that it is not cyanide. We are also ruling out poachers because the tusks were intact.”

The mysterious deaths appear similar to the deaths last month of more than 275 elephants in neighbouring Botswana.

Scientists are still investigating the deaths of the elephants in the Okavango Delta area of Botswana and poaching, poisoning and anthrax have been ruled out.

Botswana has the world’s largest elephant population, estimated at 156,000, and Zimbabwe has the second largest, estimated at 85,000. Last year about 200 elephants in Zimbabwe died of starvation as a result of a drought.