Dr. Sam Zaramba, the government's director of health services, told Reuters the doctor had died in Kampala's Mulago Hospital after looking after a patient in its isolation ward.

Besides the two, all other cases and deaths had occurred where the outbreak started in Uganda's western Bundibugyo district, bordering the Democratic Republic of Congo, he said.

"The total number of suspected cases is now 93 that fit the definition," he said. "Twenty two have died. Out of them, four (are) health workers, one a doctor. He died in Mulago."

Only 58 cases have so far been confirmed in laboratory tests, the government says. But more people falling ill and a rising death toll since the outbreak started in August has caused panic in the east African country.

The government confirmed the fever was Ebola a week ago.

"All medical staff dealing with Ebola have been issued with protective gear," Zaramba said.

Genetic analysis of samples taken from some victims shows this virus is a previously unrecorded type of Ebola, making it a fifth strain, U.S. and Ugandan health officials say.

The World Health Organisation is concerned about the way the virus keeps mutating.

But Ugandan officials say the unusually low death rate of this type -- at roughly 22 percent when the virus normally kills between half and 90 percent of those infected -- shows it is less lethal than previous epidemics.

Uganda was last hit by Ebola outbreak in 2000, when 425 people caught it and just over half died.

This year, an epidemic broke out in Congo -- where some of the first recorded cases in 1976 gave the virus its name after the country's Ebola river. It killed 187 people and infected up to 264.