The World Health Organization (WHO) on Monday convened a meeting of ethicists and scientists to assess the role of experimental therapies in the Ebola outbreak response, a UN spokesman said.

"The recent treatment of two health workers infected with the Ebola virus with experimental medicine has raised questions about whether medicine that has never been tested and shown to be safe in people should be used in the outbreak," said UN Spokesperson Stephane Dujarric at a daily briefing.

The panel discussed whether it is ethical to use unregistered interventions with unknown adverse effects for possible treatment or prophylaxis, and what criteria should guide the choice of intervention, Dujarric said.

"Under the leadership of the WHO, activities in the field, in all four countries impacted by the outbreak, include infection prevention and control, community mobilization and tracing of people who have been in contact with Ebola patients," the spokesman added.

The largest Ebola outbreak ever recorded at present began in Guinea in December 2013, and now involves transmission in Guinea, Liberia, Nigeria, and Sierra Leone.

Statistics from the WHO showed that as of Aug. 4, countries have reported 1,711 cases (1,070 confirmed, 436 probable, 205 suspect), including 932 deaths.

The WHO warned on Friday that the disease is now a "public health emergency of international concern" and called for a coordinated international response to stop and reverse the international spread of Ebola.

The Ebola virus, with a fatality rate up to 90 percent, spreads through mucous and other body fluid or secretions such as stool, urine, saliva and semen of infected people.