The UN chief António Guterres has demanded the immediate release of Mali's President Bah Ndaw and Prime Minister Moctar Ouane, who have been detained by soldiers.
The BBC reports that the two men who are leading an interim government that took power after a military coup last August were driven by soldiers to a military camp near the capital, Bamako.
The detention followed just hours after a government reshuffle in which two army officers who took part in the coup were replaced.
PM Ouane is reported to have told AFP in a phone call that soldiers "came to get him". The news agency said the line was then cut.
Defence Minister Souleymane Doucouré has also reportedly been detained.
The African Union, the Economic Community of West African States (Ecowas), the EU, and the US have also condemned the arrests, saying Mali's top politicians must be released without any preconditions.
Ibrahim Boubaca Keïta was ousted as president last year following weeks of anti-government protests over rising insecurity, alleged corruption, and a failing economy.
Many celebrated his ouster but tensions have since grown from the alleged slow pace of change over the last nine months, with Mali's workers' union getting to its second week of strike.
During the 18-month transition, the interim government agreed to appoint a new broader-based cabinet amidst threats of renewed protests. The ministers of defence and security, Col. Sadio Camara and Col. Modibo Kone, were fired respectively.
The opposition group, M5 RFP, also faulted the interim government for not rewarding them with any ministerial positions.