The authorities in Niger say recent flooding in the capital, Niamey, has forced over 225,000 people from their homes.
The number of deaths has risen to 45.
Parts of the city have been submerged since Tuesday when the River Niger breached its banks. Heavy rain since then has caused further damage.
Rescuers used canoes to help victims, the AFP news agency reports.
It adds that the authorities had last month issued a warning that about 300,000 people were at risk from flooding since heavy rains began.