The death toll from the Ebola outbreak tearing through West Africa has passed the 1,500 mark while the number of cases has soared past 3,000, the World Health Organization said Thursday.

"The outbreak continues to accelerate," the UN health body said in its latest update on the killer virus.

As of August 26, a total of 1,552 people had died in Guinea, Liberia, Sierra Leone and Nigeria from the epidemic that reared its head at the beginning of the year, while 3,062 had become infected.

On August 20, the toll stood at 1,427 deaths out of 2,600 cases.

A separate outbreak of Ebola, one of the deadliest viruses known to man, in the Democratic Republic of Congo, where 13 people have died, was not included in Thursday's tally.

"More than 40 percent of the total number of cases have occurred within the past 21 days," WHO said, adding that most cases were concentrated in just a few localities.

It said the overall fatality rate stood at 52 percent, but varied from 66 percent in Guinea, where the outbreak began, to 42 percent in Sierra Leone.

To date, Guinea has 648 cases including 430 deaths, while Sierra Leon has seen 1,026 cases and 422 deaths.

Liberia has so far counted 1,378 cases and 694 deaths, while Nigeria has seen 17 cases and six deaths, WHO said.