* Military leaders say they must return to lead transition
* Deadlock as regional bloc, donors seek civilian rule
BAMAKO, May 10 (Reuters) - The officer who led a military coup in Mali in March wants to take back power when the term of a caretaker president, appointed under an agreement brokered by regional mediators, runs out later this month, aides said on Thursday
The military nominally handed over power last month to Dioncounda Traore. Regional bloc ECOWAS, Mali’s foreign donors and many political parties want him to stay in office to oversee a transition back to civilian rule even after his 40-day mandate expires on May 21.
Efforts in the capital Bamako to prepare a return to civilian rule have made little progress and coup leader Captain Amadou Sanogo has continued to hold sway.
“Our proposition is that the only neutral umpire in this is the army. Given the situation, only he (Sanago) can run this “ Bakary Mariko, a spokesman for the CNRDRE body that represents the coup leaders, said by telephone.
“For now, it is not negotiable.”
The CNRDRE position was confirmed by another official close to Sanogo.
The coup has left the West African nation diplomatically isolated and allowed a mix of separatist and Islamist rebels to seize all the main towns in the desert north, sweeping with them fighters linked to al Qaeda.
The April 6 agreement that saw soldiers hand power to Traore for an interim period stipulates that if polls are not held within 40 days, Sanogo and ECOWAS would together decide on who should lead the transition back to civilian rule.
However, at a summit last month, West African leaders said they wanted Traore to remain in place for as long as a year, a proposition that was rejected by the junta.
Traore was sworn in on April 12 but the military, enjoying the support of some political parties, has continued to flex its muscles, arresting a number of senior civilian and military figures linked to ousted President Amadou Toumani Toure.
ECOWAS mediators, currently holding talks in Mali, did not make any public statement.
But a source close to the delegation said: “It is the choice of the person who will lead the transition that is the problem.”
Most of aid-dependent Mali’s donors have cut non-humanitarian support since the coup.
ECOWAS has said that it is ready to send soldiers to help Mali wrest control of its north back from Tuareg-led rebels but it first wants to see the country back in civilian control.
Most of Mali’s mainstream political parties have backed the ECOWAS call for Traore to remain in charge but the junta says is must oversee the transition due to the conflict in the north and its claims of corruption within the political class.
Mali’s crisis erupted as the country was already grappling another bout of food shortages. Western and regional states fear its desert north has become a haven for al Qaeda fighters and international criminal gangs. (Reporting by Tiemoko Diallo; Writing and additional reporting by David Lewis; Editing by Angus MacSwan)