An outbreak of the deadly Ebola virus in the Democratic Republic of Congo risks spreading to major towns if not brought under control soon after the death toll doubled within a week, the World Health Organisation warned on Thursday.

The number of people killed by the contagious virus for which there is no known treatment has now risen to 31, including five health workers. Ebola causes massive bleeding and kills up to 90 percent of its victims.

"The epidemic is not under control. On the contrary the situation is very, very serious," Eugene Kabambi, a WHO spokesman in Congo's capital Kinshasa, told Reuters by phone.

[link to www.trust.org]