By Brian Benza
SERONGA, Botswana (Reuters) - Botswana wildlife officials investigating hundreds of unexplained elephant deaths have verified six more carcasses and say it is still not clear what is killing the animals, around two months after the first bodies were spotted.
Officials told reporters near the Okavango Delta on Thursday that they had now verified 281 carcasses and that the deaths were concentrated in an area of 8,000 square km that is home to about 18,000 elephants.
Flying over the area in a helicopter, a Reuters reporter saw one carcass splattered in droppings from vultures, which had eaten some of the flesh, and red paint from officials marking verified carcasses. Hundreds of live elephants wandered nearby.
"We are not dealing with a common thing, it looks like it's a rare cause," said Mmadi Reuben, principal veterinary officer at the Department of Wildlife and National Parks, adding the death rate in the affected area was below 2%.
"We cannot rule out anything at this stage, it could be a virus, vegetation, overnutrition after last year's drought ... We have asked the community not to interact with the carcasses."
He said officials were expecting to receive test results this week on samples sent to South Africa and Canada.
Some campaign groups have criticised the government for acting too slowly to solve the mystery of the dying elephants, an accusation Reuben has denied.
Although the number of deaths so far represents a fraction of the estimated 130,000 elephants in Botswana, there are fears more could die if authorities cannot establish the cause soon.
Wave Kashweka, a senior veterinary officer in Botswana's North-West district, said officials had found elephants which appeared to have died recently, adding aerial surveys would try to find more carcasses.
In their initial inquiries, authorities ruled out poaching and anthrax among possible causes.
Cyril Taolo, acting director of the wildlife department, said the government had contacted neighbours Zimbabwe, Angola, Namibia and Zambia but they had not seen similar elephant deaths.
Africa's overall elephant population is declining due to poaching, but Botswana, home to almost a third of the continent's elephants, has seen numbers grow from 80,000 in the late 1990s.
(Writing by Alexander Winning in Johannesburg; Editing by Janet Lawrence)