Mali’s President Bah Ndaw and Prime Minister Moctar Ouane, tasked with steering the return to civilian rule after a coup last August, had been held since Monday and resigned “before the mediator”, said Baba Cisse, special advisor to junta boss Assimi Goita.
Cisse said negotiations were under way for their release and the formation of a new government in the poor Sahel country.
A member of the Economic Community of West African States (ECOWAS) mediation mission confirmed the president’s resignation to AFP, requesting anonymity.
According to AFP, the team travelled early Wednesday to the Kati military camp around 15 kilometres (nine miles) from the capital Bamako to visit the two detainees.
Ndaw and Ouane had been heading the interim government with the declared aim of restoring full civilian rule within 18 months.
Goita, who holds the rank of vice president in the transitional government, accused Ndaw and Ouane of failing to consult him on a reshuffle.
The UN Security Council was set to hold an emergency meeting later Wednesday at the request of former colonial power France and others.
On Monday, the United Nations, African Union, ECOWAS, the EU and the United States issued a rare joint statement, attacking the detention and demanding the release of Ndaw and Ouane.
Young military officers ousted president Ibrahim Boubacar Keita last August after weeks of demonstrations over perceived government corruption and his handling of the jihadist insurgency.