St Louis is known for its decaying charm and is a World Heritage site
St Louis in Senegal is the city most threatened by rising sea levels in the whole of Africa, a senior United Nations official says.
"Climate change is the principal reason," UN Habitat's Alioune Badiane told a conference in St Louis, AFP news agency reports.
The city is built on an island between the mouth of the Senegal River and the Atlantic Ocean.
It was made a World Heritage site in 2000 by Unesco, the UN cultural agency.
The city, near Senegal's border with Mauritania, was founded by the French in the 17th century.
It was once the colonial capital of French West Africa and Mauritania.
But in the early years after Senegal's independence in 1960, Dakar, further along the coast, became the principal city.
Correspondents say it is known for its architectural charm and attracts more than 10,000 foreign tourists every year.
Talking at a conference at St Louis University, Mr Badiane said that the St Louis "was the African city most threatened by the rising levels of the sea".
He said a channel built in 2004 to save the city from flooding had actually made the situation worse.
"It is a double handicap for St Louis to be between the ocean currents and the River Senegal," he said.