Torrential rains earlier this month triggered floods that killed at least 18 people in areas of southern Morocco that straddle the Sahara desert.

Regional authorities in Tata province said heavy rainstorms late Friday led to "exceptional" floods that caused houses to collapse and swept away the bus.

A statement which gave the toll of dead and missing said 13 others were rescued.

The rare heavy rains come as the North African kingdom grapples with its worst drought in nearly 40 years, threatening its economically crucial agriculture sector.

Morocco is one of the world's most water-stressed nations, with frequent droughts affecting a third of the population employed in agriculture.

Experts say climate change is making extreme weather, such as storms and droughts, more frequent and intense.

For water levels in dams to rise and groundwater to replenish, experts say the rains would need to continue over a longer period of time.