LONDON -- The World Health Organization says the ongoing outbreak of yellow fever in central Africa is "serious and of great concern," but does not warrant being declared a global emergency.

On Thursday, the UN health agency convened an expert committee to consider whether the epidemic of yellow fever, an acute hemorrhagic disease, qualifies as an international health emergency.

That is defined by WHO as an "extraordinary" event with the potential to cross borders and requiring immediate action. WHO previously declared crises including the 2014 Ebola outbreak and the Zika virus to be global emergencies.

The current yellow fever outbreak, first identified in Angola last December, has sickened more than 2,000 people and killed nearly 300. The mosquito-spread disease has also been exported to Congo, Kenya and China.