Twelve more elephants have died in Zimbabwe, taking the total death toll from a suspected bacterial infection outbreak to 34, wildlife authorities said Monday.

"A total of 34 carcasses have been found... but some others have not been located," Zimbabwe Parks and Wildlife Management Authority director Fulton Upenyu Mangwanya told parliament.

The animals died between August 24 and September 23 this year in and around the wildlife-rich forests between the famous northwestern Hwange National Park and the town of Victoria Falls.

"They were found lying on their bellies" suggesting they had an "extremely sudden death," Mangwanya said.

Tests conducted in Zimbabwe so far point to a disease called haemorrhagic septicaemia, which is caused by bacterial infection, he said.

Rangers have ruled out cyanide poisoning or poaching because the animals were found with their tusks intact.

Mangwanya said wild animals are more susceptible to disease during the country's dry and hot season, which is roughly from August to November.

In recent years Zimbabwe has suffered through successive droughts made more severe by global warming, leaving animals with less water and vegetation.

Samples have been sent to a laboratory in Britain and others will be dispatched to South Africa and the United States for further tests and analysis.

Zimbabwe counts more than 84,000 elephants -- almost double the southern African country's ecological carrying capacity of between 45,000 and 50,000.

Neighbouring Botswana, home to the world's largest elephant population of around 130,000, lost around 330 elephants early this year from cyanobacteria poisoning.