MONROVIA, Aug 11 (Reuters) - U.S. President Barack Obama and the Food and Drug Administration have approved a request from Liberia's government to send sample doses of an experimental drug to treat Liberian doctors infected with Ebola, the Liberian presidency said in a statement.

The statement, posted on the Liberian presidency's official website, said the experimental drugs would be delivered to the West African country this week by a representative of the U.S. government, following a direct appeal to Obama on Friday by Liberian President Ellen Johnson Sirleaf.

Margaret Chan, the head of the World Health Organization, has also authorized the dispatch of additional doses of the experimental drug to Liberia to support the treatment of affected doctors, the statement said. Those doses will be delivered by a WHO expert this week. (Reporting by Clair MacDougall in Liberia and Daniel Flynn in Dakar)

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