President Sidi Ould Cheikh Abdallahi and Prime Minister Yahya Ould Ahmed Waghf were seized by troops early on 6 August in what appears to have been a bloodless coup, according to reports from the country.
President Abdallahi has been in power since winning an election in March 2007.
Three generals staged the coup after Abdallahi issued an order earlier the same day removing them from their posts as head of the Presidential Guard, head of the armed forces and head of the National Guard.
In a phone call from the presidential palace, Abdallahi's daughter Amal Mint Cheikh Abdallahi told Radio France International: "The president has just been arrested by a commando who came to fetch him, arrested him here and took him away."
Mauritania is the world's newest oil producer and one of the countries worst affected by high food prices.
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