JOHANNESBURG (AP) — The World Health Organization has issued an unusual statement raising questions about whether Tanzania is covering up possible cases of the deadly Ebola virus.

The statement Saturday says Tanzania's government has not shared its clinical data, the results of its investigations or the possible contacts of a number of patients with Ebola-like symptoms.

Tanzania's government, which has said it has no Ebola cases, could not immediately be reached for comment Sunday. The cases would be the first-ever Ebola cases confirmed in the East African country.

The WHO statement says the lack of information makes it difficult to assess potential risks in an Ebola outbreak in Africa that has been declared a rare global health emergency.

The Ebola outbreak based in neighboring Congo has infected over 3,000 people and killed nearly 2,000 of them.