One of Afghanistan's worst earthquakes killed more than 800 people and injured at least 2,800, authorities said on Monday, as helicopters ferried the wounded to hospital after they were plucked from the rubble of homes being combed for survivors.

Toll likely to rise, with significant damage reported across mountainous provinces of Kunar and Nangahar, sources say.

Reports showed 250 dead and 500 injured, said Najibullah Hanif, the provincial information head of Kunar, adding that the tally could change.