Mali's prime minister announced his resignation on Tuesday, hours after being arrested by soldiers while trying to leave the divided and unstable West African nation for France.
The development in the Sahel state, whose desert north was occupied by Al-Qaeda-linked Islamists following a March coup, seemed likely to complicate African and international efforts to organize a military intervention to reunite the country.
"I, Cheick Modibo Diarra, hereby resign with my entire government on Tuesday, 11 December 2012," a nervous-looking Diarra said in a statement broadcast on state television early on Tuesday morning.
News of Diarra's resignation came hours after he was arrested late on Monday as he tried to leave the country for France. It was not immediately clear whether he made the statement of his own volition or was forced to do so.
Bakary Mariko, a spokesman for the group of soldiers that seized power in the March coup, and which remains powerful despite officially handing power back to civilians in April, said Diarra had been arrested for not working fully to address the nation's problems.
"The country is in crisis but he was blocking the institutions," Mariko said. He added Diarra had been taken to the ex-junta's headquarters in Kati, a military barracks town just outside Bamako, after his arrest.
Asked if the overnight arrest was a second coup, Mariko said: "This is not a coup. The president is still in place but the prime minister was no longer working in the interests of the country."
There was no immediate reaction from interim civilian President Diouncounda Traore.
Coup leader Captain Amadou Sanogo has been repeatedly accused of meddling in politics since he stepped down and was officially tasked with overseeing reforms of Mali's army.
Residents in Bamako said the town was quiet in the early hours of Tuesday morning.
There have been divisions for months between the former junta, interim President Traore and Diarra, a former NASA scientist and Microsoft chief for Africa.
Fearing Mali has become a safe haven for terrorism and organized crime, West African leaders have signed off on a plan to send 3,300 soldiers to Mali to revamp Mali's army and then support operations to retake the north from the Islamist rebels.
But support for the plan is not universal.
France is keenest to see military action to tackle the Islamist groups, including Al-Qaeda's North African wing, AQIM. But the United States and the United Nations have expressed concern, saying the plan lacks necessary detail for a complex operation.
The United States warned on Monday that Mali was "one of the potentially most explosive corners of the world."
Some of Mali's politicians support the idea of a foreign-backed military operation while others, including much of the military, say they need only financial and logistical support and insist that Mali can carry out the offensive itself.
Diarra was made prime minister in April after the military officially handed power back to civilians. As the son-in-law of Moussa Traore, a former Malian coup leader and president, he appeared to have good ties with the military.
However, tensions became particularly acute in recent weeks, with analysts saying Diarra, a relative newcomer to Malian politics after years abroad, seemed keen to establish a political base of his own ahead of any future elections.