The military ruler of Mauritania called Friday for his countrymen to stamp out slavery — a rare official acknowledgment that the long-outlawed practice continues in the northwest African country.

"Yes to the abolition of slavery, of all slaveries," said Col. Ely Ould Mohamed Vall, adding that he will be the first to back anti-slavery groups working in Mauritania. Vall spoke to a crowd of thousands in the city of Akjoujt, about 250 kilometers (155 miles) north of the capital of Nouakchott, urging them to turn out to vote for upcoming constitutional amendments.

"I protest against slavery whatever type it is, whether in the head, ideas, or behavior. And I ask all Mauritanians to do the same," Vall said to the group. "We must finish with these types of ideas and behaviors," Vall said.

CountryWatch: Mauritania

Mauritania outlawed slavery in 1981, and the official government stance has been that the practice no longer exists within its borders. Former President Maaoya Sid'Ahmed Ould Taya, deposed by Vall in a bloodless coup in August, did not speak of slavery as a continuing problem.

Slavery in the Muslim country has traditionally followed ethnic lines, with lighter-skinned maurs owning darker Africans and ownership passing down through generations.

Vall, who has said he will not run for Mauritania's presidency in elections next year, did not provide any specific plan for eradicating slavery in the desert nation.