Flash floods have claimed 187 lives and affected 635,273 people in west Africa since the rainy season started in June, the UN Office for the Coordination of Humanitarian Affairs announced Tuesday.

The nation with the highest death toll, including people struck by lightning, is Sierra Leone, with 103 people, followed by Ghana (24), Mali (20), Ivory Coast (19), Burkina Faso (eight), Niger (seven) and Senegal (six), the UN organisation said in a statement.

While the death toll in Senegal was low, the country topped the list for the number of people affected by flooding at 264,000, followed by Burkina Faso (150,000), Niger (79,129), Ghana (55,000), Guinea (27,464), Benin (20,000), Mali (12,506), Gambia (12,183), Mauritania (9,000), Ivory Coast (2,000) and Sierra Leone (1,455).

The OCHA in Dakar, Senegal's capital, said it took account of "the destruction of personal and public property such as homes, crops, (and) socio-economic infrastructure such as schools, houses, hospitals, roads and bridges."

In 2007, serious flooding killed about 300 people across Africa, from west to east, and affected about 1.5 million people, according to the UN agency.