The World Health Organisation (WHO) called on Thursday for pharmaceutical companies and regulatory agencies to work together to accelerate development of safe and efficient drugs and vaccines against Ebola.

Ten experimental treatments - eight drugs and "two promising candidate vaccines" - have shown potential against the virus but remain under investigation, the WHO said in a document distributed at the start of a two-day meeting in Geneva.

They include the antibody drug ZMapp made by U.S.-based Mapp Biopharmaceutical Inc., which has been given to several Ebola patients for "compassionate care" but whose clinical effectiveness is "still uncertain", it said. "Efforts to scale up production (of ZMapp) may yield increased supplies of potentially a few hundred doses by the end of 2014."

Evidence of the effectiveness of the medicines and vaccines is "suggestive but not based on solid scientific data from clinical trials," the WHO said. Existing supplies of all experimental medicines are extremely limited or exhausted.

The virulent disease, which has killed at least 1,900 people in West Africa since March, could affect 20,000 by the time it is contained in the next six to nine months, the WHO has said.

"Accelerating the development of experimental/not approved Ebola Virus Disease therapies and vaccines require a concerted effort by product developers and regulatory agencies, in cooperation with the WHO," the WHO paper said.

Decisions on which products go into accelerated development should be transparent and involve the West African countries affected by the epidemic, it said.

"While there is an urgent need for product to be used on a compassionate basis, the ultimate goal should be product approval so that countries affected by Ebola Virus Disease have products which have been demonstrated safe and effective at their disposal."

"THE HOPE OF WHAT WE ARE GOING TO HAVE"

Marie-Paule Kieny, WHO assistant director-general who is chairing the closed-door talks attended by more than 150 experts, said the meeting would focus on developing the most promising drugs in the quickest possible time.

"Developed in terms of getting them to registration and developed in terms of putting them in the treatment center as much as possible in order to make a difference in the lives of people," she said.

The WHO paper said that while supplies of experimental drugs are limited "the prospects of having augmented supplies of vaccines quickly look slightly better".

Human safety trials are due to begin this week on a vaccine from GlaxoSmithKline Plc and later this year on one from NewLink Genetics Corp. Johnson & Johnson said on Thursday that clinical trials of its vaccine would commence in early 2015, accelerated from late 2015 or early 2016.

NewLink Genetics Corp NLNK.O said the U.S. Food and Drug Administration (FDA) allowed the Iowa-based company to start testing an experimental Ebola vaccine in humans.

NewLink founder Charles Link told Reuters on the sidelines of the Geneva talks on Thursday: "The clinical trials do take some time. Everybody is trying as hard and furiously as possible to move those trials forward as rapidly as possible with the regulations, scientific and ethical constraints.

A treatment by Tekmira Pharmaceuticals of Vancouver, Canada, that targets two viral genes to stop the virus from replicating, may be available in limited supplies, the WHO said. "There is potential for the production of 900 courses by early 2015."

(Additional reporting by Antony Paone in Geneva; Editing by Dominic Evans)