A wave of water released by a burst dam has killed at least 23 people in Cameroon's capital Yaounde after heavy rains, the army's rescue unit said on Monday.

A colonial-era dam gave way at about 4pm local time on Sunday, releasing water from a small lake, said Assola Joseph, a local leader in the Mbankolo neighbourhood.

Residents and rescue workers were picking through the debris of rubble, broken timber, uprooted banana trees and corrugated sheeting on a steep hillside on Monday morning.

A Reuters journalist at the scene said at least five bodies had been recovered, and at least 30 houses destroyed.